ASME certification (Boiler & Pressure Vessel Code stamps such as S, U, U2, N, PP) shows that a manufacturer's quality system and products were audited by ASME. Listed here: active and recent certificate holders located in Korea. Source: https://www.asme.org/ (certificate holder search), retrieved 2026-10-13. 506 companies · 1,256 certificates. Companies with a verified profile on this site are linked; the rest appear here only (409).
Certificates expire and get withdrawn — always confirm the current status with the issuing body before relying on it. This list is a starting point for sourcing, not a quality rating.
| Company | Location | Products / scope | Certs | Latest expiry |
|---|---|---|---|---|
| A-ONE Co., Ltd. · | Danwon-gu, Ansan-si, Gyeonggi-do | U2 Boiler | 1 | 2026-06-12 |
| Aero PHE Corporation · | Busan | U Boiler | 1 | 2017-03-03 |
| AHA M-tech Co., Ltd. · | Dangjin-Si, Chungcheongnam-Do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 6 | 2017-09-08 |
| Alfa Laval CorHex Ltd. · | Daejeon | U Boiler | 1 | 2028-02-15 |
| ALPEC Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | S Boiler; U Boiler; U2 Boiler | 3 | 2019-06-02 |
| Answer Co., Ltd. · | Busan | S Boiler; U Boiler; U2 Boiler | 3 | 2027-12-10 |
| Armstrong International Korea Co., Ltd · | Siheung-Si, Gyeonggi-Do | PP Boiler; S Boiler; U Boiler | 3 | 2017-12-19 |
| ASFLOW Co., Ltd. | Hwaseong-si, Gyeonggi-do | BPE BPE | 1 | 2027-02-28 |
| ASIA HEAVY INDUSTRY CO., LTD. · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2027-01-21 |
| Asia Protech Co., Ltd. · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2027-02-24 |
| ASPE Inc. · | Chungju-si, Chungcheongbuk-do | PP Boiler; U Boiler | 2 | 2029-05-26 |
| AST Co., Ltd. · | Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2026-11-20 |
| AxFil Co., Ltd. · | Gyeonggi-do | U Boiler | 1 | 2029-03-06 |
| Bando E&T Co.,Ltd. · | Ulsan | U Boiler | 1 | 2027-08-13 |
| BHI Co., Ltd. | Gyeongsangnam-do, Haman-gun, Gyeongsangnam-do, Sacheon-si, Gyeongsangnam-do | N Nuclear; N3 Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 13 | 2028-07-10 |
| BLUESP Co., Ltd. · | Yeongam-gun, Jeollanam-do | PP Boiler; S Boiler; U Boiler | 3 | 2027-11-18 |
| BMS Engineering Co., Ltd. · | Busan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2027-09-23 |
| BMS Power Co., Ltd. · | Ulju-gun, Ulsan | S Boiler; U Boiler | 2 | 2027-08-06 |
| BMT Co., Ltd. · | Jangan-eup, Gijang-gun | N Nuclear; NPT Nuclear; NS Nuclear | 3 | 2027-12-18 |
| Bowon Co., Ltd. · | Yeongam-Gun, Jeollanam-Do | PP Boiler; S Boiler; U Boiler | 3 | 2016-11-12 |
| BU HEUNG CO.,LTD · | Busan | PP Boiler; S Boiler | 2 | 2026-12-07 |
| Bumhan Mecatec Co., Ltd. | Gyeongsangnam-do | H2 Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2027-09-26 |
| Bumhan Mecatec Co.,Ltd. | Changwon-si, Gyeongsangnam-do | NPT Nuclear; NS Nuclear | 2 | 2028-08-15 |
| Bumhan Mecatec Co.,Ltd. Changwon Plant II | Changwon-si, Gyeongsangnam-do | U Boiler; U2 Boiler | 2 | 2027-12-22 |
| Buyoung CST Co., Ltd. · | Busan | U Boiler | 1 | 2017-09-02 |
| BYUKSONG Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-05-28 |
| CAELUM Co., Ltd. · | Busan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-09-30 |
| Century Corporation · | Asan-si, Chungcheongnam-do | N Nuclear; NPT Nuclear | 2 | 2029-10-10 |
| Changshin Precision Co., Ltd. · | Gyeongsangnam-do | U Boiler | 1 | 2027-11-13 |
| Changwon Engineering Co., Ltd. · | Gangseo-Gu, Busan | PP Boiler; S Boiler; U Boiler | 3 | 2016-08-27 |
| Cheonbok Machinery Co. Ltd. · | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2019-03-06 |
| Cheonbok Tech Co., Ltd. · | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2028-04-15 |
| CORE Plant Co., Ltd. · | Ulju-gun, Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-05-10 |
| COS Corporation · | Jeollanam-Do | U Boiler; UM Boiler | 2 | 2029-03-23 |
| Creative Intelligent Technology Co., Ltd. · | Ulsan | U Boiler | 1 | 2026-09-11 |
| CRYOS Co., Ltd. · | Busan | S Boiler; T Boiler; U Boiler; U2 Boiler | 4 | 2028-12-13 |
| CSTech Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2017-07-22 |
| Customer Satisfaction · | Yeosu-si, Jeollanam-do | S Boiler; U Boiler | 2 | 2018-05-13 |
| CVE Co., Ltd. · | Hwaseong-si, Gyeonggi-do | U Boiler; U2 Boiler | 2 | 2028-03-17 |
| D'Hondt Thermal Solutions Co., Ltd. · | Gunsan-si, Jeollabuk-do | S Boiler; U Boiler; U2 Boiler | 3 | 2028-08-01 |
| Dae Dong Entec Co., Ltd. · | Busan | S Boiler; U Boiler | 2 | 2027-01-12 |
| Dae Kong E&C Ltd. · | Ulju-gun, Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2029-06-21 |
| Dae Ryung Corporation · | Uiryeong-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-06-26 |
| Daechang HRSG Corporation · | Ulsan | S Boiler; U Boiler | 2 | 2018-06-13 |
| Daechang HRSG Corporation HQ Plant · | Ulsan | S Boiler; U Boiler; U2 Boiler | 3 | 2018-06-13 |
| Daedong Heavy Industry Co., Ltd · | Gwangyang-si, Jeollanam-do | S Boiler; U Boiler | 2 | 2016-12-17 |
| DAEDONG HEAVY INDUSTRY CO., LTD. · | Gimhea-si | PP Boiler | 1 | 2026-05-26 |
| Daega Powder Systems Co., Ltd | Chungcheongnam-Do | S Boiler; U Boiler | 2 | 2016-10-14 |
| Daehan Instrument Co., Ltd. · | Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-12-16 |
| DaeHeung Cooler Co., Ltd. · | Pocheon-Si, Gyeonggi-Do | U Boiler | 1 | 2029-02-07 |
| DaeHeung Industry Co., Ltd. · | Ulsan | S Boiler; U Boiler | 2 | 2017-09-02 |
| Daehyun E&I Inc. · | Eumseong-gun, Chungcheongbuk-do | H2 Boiler; HLW Boiler; U Boiler | 3 | 2016-12-17 |
| Daehyun Industry Co., Ltd. · | Gyeongju-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2016-12-31 |
| Daejoo Machinery Co., Ltd. · | Daegu | PP Boiler; U Boiler; U2 Boiler | 3 | 2028-01-25 |
| Daekyung Bend Co., Ltd | Yangsan-Si, Gyeongsangnam-Do | NPT Nuclear | 1 | 2017-01-07 |
| Daekyung Engineering & Construction Co., Ltd. · | Nam-gu, Ulsan | S Boiler; U Boiler; U2 Boiler | 3 | 2028-07-11 |
| DAEKYUNG M&I Co., Ltd. · | Yeosu-si Jeollanam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-03-03 |
| Daekyung Machinery & Engineering Co., Ltd./Yeosu 1st Plant · | Yeosu-si, Jeollanam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2018-04-04 |
| Daelim Royal EnP Co., Ltd. | Chilgok-gun, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2027-11-10 |
| Daerim Machinery Co., Ltd. · | Gangseo-gu, Busan | U Boiler; U2 Boiler | 2 | 2027-05-01 |
| DAERYUN CO., LTD. · | Gunpo-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-12-16 |
| DAESAN Co.,Ltd. · | Gyeongju-si, Gyeongsangbuk-do | S Boiler; U Boiler | 2 | 2019-01-13 |
| DAESANG ENG CO., LTD. · | Dangjin-si, Chungcheongnam-do | S Boiler; U Boiler | 2 | 2028-04-25 |
| Daesung Celtic Enersys Co., Ltd. | Cheonan-si, Chungcheongnam-do, Eumseong-gun, Chungcheongbuk-do | H2 Boiler; HLW Boiler | 4 | 2027-07-16 |
| Daesung Machinery Co., Ltd. · | Siheung-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2028-09-12 |
| Daewon Industrial Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2018-07-10 |
| Daewoo Engineering & Construction Co., Ltd. · | Seoul | NA Nuclear; NPT Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 6 | 2027-10-23 |
| DAEWOONG CT Co., Ltd. · | Gangseo-gu, Busan | S Boiler; U Boiler; U2 Boiler | 3 | 2028-03-22 |
| DAEWOONG ET Co., Ltd. · | Gangseo-gu, Busan | S Boiler; U Boiler; U2 Boiler | 3 | 2029-09-11 |
| Daeyeol Boiler Co., Ltd · | Ansan-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-12-18 |
| DAEYEOL BOILER CO.,LTD. · | Seosan-si, Chungcheongnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2029-07-14 |
| Dalim Co., Ltd · | Gyeonggi-do | S Boiler; U Boiler | 2 | 2018-04-09 |
| Darin Steel Tech Co., Ltd. · | Gangseo-gu, Busan | PRT Boiler | 2 | 2027-09-04 |
| DASAN Co., Ltd. · | Gyeonggi-do | U Boiler | 1 | 2028-07-28 |
| DASCO Co., Ltd. · | Gangseo-gu, Busan | S Boiler; U Boiler | 2 | 2027-12-10 |
| DHHI Co.,Ltd. · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2027-01-13 |
| DHP Engineering Co., Ltd. | Gimhae-si, Gyeongsangnam-do | U Boiler | 1 | 2027-06-30 |
| DJF Co., Ltd. · | Gangseo-gu, Busan | S Boiler; U Boiler | 2 | 2027-07-30 |
| DK BRAZING CO.,LTD · | Bucheon | H2 Boiler; HLW Boiler | 2 | 2028-10-07 |
| DK-Lok Corporation | Gimhae-si, Gyeongsangnam-do | N Nuclear; NPT Nuclear; NS Nuclear | 3 | 2027-03-10 |
| DKME Co., Ltd. · | Ulju-gun, Ulsan, Ulsan | S Boiler; U Boiler; U2 Boiler | 9 | 2028-11-08 |
| DL E&C Co., Ltd. · | Seoul | NA (Quality Assurance Program) Nuclear; NA Nuclear; NPT (Quality Assurance Program) Nuclear; NPT Nuclear; PP Boiler; S Boiler; U Boiler | 7 | 2028-07-05 |
| DLHI Co., Ltd. · | Sacheon-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-12-05 |
| DLHI Co., Ltd. (Sacheon Plant) · | Sacheon-si, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2027-11-30 |
| DMT Co., Ltd. · | Yeosu-si, Jeollanam-do | S Boiler; U Boiler | 2 | 2027-05-16 |
| Dong Yang Steel Pipe Co., Ltd. · | Cheonan-si, Chungcheongnam-do | PRT Boiler | 1 | 2025-10-10 |
| Dong-A Chemical Machinery Co., Ltd. · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2016-06-26 |
| Dongbang Ship Machinery Co., Ltd. · | Busan | PP Boiler; S Boiler; U Boiler | 3 | 2016-07-21 |
| Donghae Machinery Co., LTD. | Haman-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 6 | 2018-07-31 |
| DONGHAE MACHINERY Co., Ltd. | Haman-gun, Gyeongsangnam-do | U Boiler | 1 | 2027-03-15 |
| DongHwa Entec Co., Ltd. | Busan, Gangseo-gu, Busan | PP Boiler; PRT Boiler; U Boiler; U2 Boiler | 4 | 2027-08-20 |
| DongHwa PHE Co., Ltd. · | Busan | U Boiler | 1 | 2029-05-26 |
| Dongil Industry Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2028-09-05 |
| DongJin Cryotec Co., Ltd · | Goseong-gun, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2017-02-08 |
| DONGKUK INT.CO.,LTD · | Gunsan-si, Jeollabuk-do | U Boiler | 1 | 2019-06-20 |
| Dongkuk S&C Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | S Boiler; U Boiler | 2 | 2019-05-08 |
| Dongmyung Machinery Co., Ltd. · | Jeonju-si, Jeollabuk-do | S Boiler; U Boiler | 2 | 2016-02-18 |
| Dongsan Tech Co., Ltd. · | Gyeongsangnam-do | U Boiler | 1 | 2027-09-05 |
| Dongsung Precision Industry Co., Ltd. · | Gyeongju-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-02-09 |
| DONGWON PARTS Co., Ltd. | Pyeongtaek-si, Gyeonggi-do | U Boiler | 1 | 2028-06-13 |
| DONGWOO ENT CORP. · | Ulsan | S Boiler; U Boiler | 2 | 2026-08-15 |
| DooKoo Korea Co., Ltd. | Siheung-si, Gyeonggi-do | PP Boiler; U Boiler | 2 | 2028-03-24 |
| Doosan Enerbility Co., Ltd. | Changwon-si, Gyeongsangnam-do | N Nuclear; N3 Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear; S Boiler; U Boiler; U2 Boiler | 10 | 2027-05-27 |
| Doosan Engineering & Construction Co., Ltd. · | Changwon-Si, Gyeongsangnam-Do | A Boiler; PP Boiler; S Boiler; U Boiler; U2 Boiler | 5 | 2018-07-22 |
| Doosan Mecatec Co., Ltd. CHangwon Plant III · | Changwon-Si, Gyeongsangnam-Do | S Boiler; U Boiler; U2 Boiler | 3 | 2018-05-24 |
| Dream Engineering Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2018-06-05 |
| Dream Engineering Co.,Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2029-07-13 |
| DS Heavy Industries Co., Ltd. · | Yeongam-Gun, Jeollanam-Do | S Boiler; U Boiler | 2 | 2016-11-01 |
| DS21 Co., Ltd. · | Incheon | U Boiler | 1 | 2026-10-23 |
| DTS Inc. · | Gunsan-si, Jeollabuk-do | S Boiler; U Boiler; U2 Boiler | 3 | 2027-02-04 |
| Duk Cheon Technology Co., Ltd. · | Gyeongju-si, Gyeongbuk | PP Boiler; S Boiler; U Boiler | 3 | 2018-03-04 |
| DUKSAN AETHER CT CO., LTD. · | Busan | U Boiler; U2 Boiler; U3 Boiler | 3 | 2027-07-19 |
| DUKSAN AETHERCT CO.,LTD. · | Buan-gun, Jeollabuk-do | RP Boiler | 1 | 2027-09-16 |
| E WHA CORPORATION · | Ganghwa-gun, Incheon | U Boiler | 1 | 2028-02-20 |
| E&CO LTD. · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2029-01-27 |
| E-WELDING Co.,Ltd. · | Haman-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2029-05-26 |
| EAST VALLEY TNC Co., Ltd. · | Gyeongju-si | PP Boiler; S Boiler; U Boiler | 3 | 2029-08-12 |
| EK Heavy Industries Co., Ltd. · | Goseong-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2019-01-29 |
| EL-TECH CO.,LTD. · | Hwaseong-si, Gyeonggi-Do | U Boiler | 1 | 2018-11-02 |
| Energy Tech Co., Ltd. · | Busan | U Boiler | 1 | 2017-10-28 |
| ENERGYEN Corporation · | Gimje-si, Jeollabuk-do, Gunsan-si, Jeollabuk-do | N Nuclear; N3 Nuclear; NPT Nuclear; S Boiler; U Boiler; U2 Boiler | 7 | 2029-08-25 |
| ENERGYN INCORPORATED · | Gyeonggi-do | U Boiler; U3 Boiler | 2 | 2028-06-28 |
| ENK Co., Ltd. · | Busan | U Boiler; U2 Boiler | 2 | 2027-07-12 |
| ENSOL Inc. · | Pohang-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-09-30 |
| ESAB CK Corporation · | Changwon-si, Gyeongsangnam-do | MO QSC | 1 | 2027-02-24 |
| FASECO Co. · | Busan | U Boiler | 1 | 2028-06-25 |
| FCP Co., Ltd. · | Daejeon | U Boiler | 1 | 2028-03-05 |
| FDC Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | UD Boiler | 1 | 2028-09-30 |
| FES Solution Co., Ltd. · | Siheung-si, Gyeonggi-do | U Boiler | 1 | 2028-08-01 |
| Fine Engineering Service Co., Ltd. · | Gangseo-gu, Busan | S Boiler; U Boiler | 2 | 2026-11-29 |
| FINE SEMITECH CORP. · | Gyeonggi-do | U Boiler | 1 | 2028-06-24 |
| Firscomp Co., Ltd. · | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2027-10-18 |
| Flotron Corporation Ltd. · | Sejong-si | U2 Boiler | 1 | 2025-10-24 |
| Flowserve Korea Ltd. · | Gyeongsangnam-do | NPT Nuclear | 1 | 2027-05-26 |
| Flowtech Co., Ltd. | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2028-10-16 |
| FLUEN Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2026-12-06 |
| Fluid & Thermal Engineering Co., Ltd. · | Gimhae-si, Gyeongsangnamdo | S Boiler; U Boiler | 2 | 2019-01-21 |
| Fuji Filter Korea Co., Ltd. · | Ulsan | U Boiler; U2 Boiler | 2 | 2028-11-16 |
| G-PEM Heavy Industries Corp. · | Yeongam-Gun, Jeollanam-Do | S Boiler; U Boiler | 2 | 2029-07-15 |
| GANA Heavy Industries Co., Ltd. · | Miryang-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-02-20 |
| GE Vernova - Gas Power · | Changwon-si, Gyeongsangnam-do | S Boiler | 1 | 2028-04-24 |
| GEOSUNG TECH CO., LTD. · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-12-07 |
| Geumsung Chemical Machinery Co., Ltd. · | Ulsan | S Boiler; U Boiler | 2 | 2017-11-26 |
| GJ Corporation Co., Ltd. · | Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2019-01-22 |
| Gloazure Co., Ltd. · | Gangwon-do | U Boiler | 1 | 2029-03-17 |
| Global Shinhwa Co., Ltd. · | Gimhae-Si, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 5 | 2029-07-09 |
| Goldstar Paper Tech. Ltd. · | Chungju-si, Chungcheongbuk-do | U Boiler | 1 | 2026-11-25 |
| Gongshin Tech Co., Ltd. · | Gimpo-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2029-08-29 |
| GS Engineering & Construction Corp. · | Jongno-gu, Seoul, Seoul | NA Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; S Boiler | 5 | 2029-08-25 |
| GS Entec Corp. | Ulju-Gun, Ulsan, Ulju-gun, Ulsan, Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 17 | 2027-01-10 |
| GSA CO., LTD. · | Gwangju-si Gyeonggi-do | U Boiler | 1 | 2019-05-20 |
| GSM Co., Ltd · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2028-11-07 |
| GTC Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2027-04-02 |
| Guman Heavy Industry Co.,Ltd. · | Goseong-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-09-22 |
| GUNHO E&C Co.,Ltd. | Ulsan | S Boiler; U Boiler | 2 | 2027-11-15 |
| GUNJEE ENG CO., LTD. · | Dangjin-si, Chungcheongnam-do | S Boiler; U Boiler | 2 | 2026-11-03 |
| Gunju Tech Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | U Boiler | 1 | 2027-08-29 |
| GUYOUNG TECH Co., Ltd. · | Daegu | U Boiler | 1 | 2027-03-10 |
| GVK INDUSTRY CO., LTD. · | Incheon | PP Boiler; U Boiler | 2 | 2027-03-25 |
| Haejeon Industrial Co.,Ltd. · | Gunsan-si, Jeollabuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2016-10-21 |
| Haeseung Hitech Co., Ltd. · | Haman-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2019-02-21 |
| HANA Envitech Co., Ltd. · | Hwaseong-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2028-02-05 |
| Hana Plant Co., Ltd. · | Hwaseong-Si, Gyeonggi-do | U Boiler | 1 | 2026-11-30 |
| Hanbal Masstech Limited · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2028-03-13 |
| Hanchang Engineering Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 6 | 2028-12-16 |
| HANGANG INDUSTRIAL CO., LTD. · | Gyeonggi-do | S Boiler; U Boiler | 2 | 2027-07-23 |
| Hanil Head Co., Ltd. · | Busan | PRT Boiler | 2 | 2028-03-25 |
| Hanil Heavy Industries Co.,Ltd. · | Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-02-09 |
| Hanjin Heavy Industries & Construction Co., Ltd. Dadaepo Factory · | Saha-Gu, Busan | A Boiler; PP Boiler; S Boiler; U Boiler; U2 Boiler | 5 | 2017-02-04 |
| HANJOO Machine Industrial Co., Ltd. · | Gimpo-si, Gyeonggi-do | S Boiler; U Boiler; U2 Boiler | 3 | 2028-11-16 |
| HanJu Tech Co., Ltd. · | Seongju-gun, Gyeongsangbuk-do | S Boiler; U Boiler | 2 | 2018-03-04 |
| HANKOOK b&tec Co., Ltd. · | Siheung -Si, Gyeonggi-Do | S Boiler; U Boiler | 2 | 2016-12-14 |
| Hankook McKAY Welding Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | S Boiler; U Boiler | 2 | 2016-11-01 |
| Hankook Taprogge Co., Ltd. | Busan | S Boiler; U Boiler | 2 | 2029-09-09 |
| HANMO CORPORATION · | Chungcheongnam-do | U Boiler | 1 | 2026-10-26 |
| HANSEONG PLANT ENGINEERING CO., LTD. | Ansan-si, Gyeonggi-do | U Boiler | 1 | 2029-03-06 |
| Hanshin Boiler Technology Corporation | Asan-si, Chungcheongnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-11-05 |
| HANSHIN MEDICAL CO., LTD. | Incheon | U Boiler; UM Boiler | 2 | 2017-12-05 |
| Hanssem Plant Co., Ltd. · | Gyeonggi-do | U Boiler | 1 | 2028-03-24 |
| HANTECH LTD. · | Ulsan | N Nuclear; N3 Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear; S Boiler; U Boiler; U2 Boiler | 8 | 2029-10-13 |
| HANUL Co.,Ltd. | Hwaseong-si | U Boiler | 1 | 2027-04-29 |
| Hanwha Techwin Co., Ltd. · | Changwon-si, Gyeongsangnam-do | U Boiler | 1 | 2016-11-06 |
| Hanyang Filters & Engineering Corp. · | Siheung-si, Gyeonggi-do | U Boiler | 1 | 2029-06-05 |
| Hanyang Industry Co., Ltd. · | Anseong-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2027-07-17 |
| HD Hyundai Heavy Industries Co., Ltd. | Dong-gu, Ulsan, Ulsan | N Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; U Boiler; U2 Boiler | 10 | 2029-01-11 |
| HEI Co,. Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-04-27 |
| HITROL Co., LTD. | Gyeonggido | PP Boiler; S Boiler; U Boiler | 3 | 2027-12-02 |
| HK Solutions Corp. · | Gangseo-gu, Busan | U Boiler | 1 | 2028-06-25 |
| Ho Yeon Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2027-11-13 |
| HSG HEAVY INDUSTRIES CO., LTD. · | . | PP Boiler; S Boiler; U Boiler | 3 | 2029-09-18 |
| Hwajin Enterprise Co., Ltd · | Busan | S Boiler; U Boiler | 2 | 2028-09-11 |
| Hwaseong Boiler Co., Ltd. | Incheon | PP Boiler; S Boiler; U Boiler | 3 | 2028-11-17 |
| HWASEUNG ENERGY CO., LTD. · | Busan | S Boiler; U Boiler | 2 | 2026-06-27 |
| Hy-Lok Corporation · | Gangseo-gu, Busan | N Nuclear; NPT Nuclear; NS Nuclear | 3 | 2028-03-17 |
| HYG CO., LTD · | Ulsan | BPE BPE | 1 | 2029-07-23 |
| HYLIUM INDUSTRIES,INC. · | Pyeongtaek-si, Gyeonggi-do | T Boiler; U Boiler | 2 | 2028-06-14 |
| Hyosung Heavy Industries Corporation | Changwon-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2026-11-12 |
| HYOWON N&V Co., Ltd. · | Yangsan-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-11-12 |
| Hyundai Engineering & Construction Co., Ltd. | Seoul | NA Nuclear; NPT Nuclear; NS Nuclear | 3 | 2027-05-23 |
| Hyundai Engineering Co., Ltd. | Seoul | NA Nuclear; NPT Nuclear; NS Nuclear | 3 | 2028-03-16 |
| Hyundai Heavy Industries Co., Ltd. Industrial Plant & Engineering Division | Ulsan | N Nuclear; N3 Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear | 7 | 2018-02-02 |
| Hyundai Heavy Industries Power Systems Co., Ltd. | Seongnam-si, Gyeonggi-do | S Boiler | 1 | 2028-06-03 |
| HYUNDAI ROTEM COMPANY · | Dangjin-si, Chungcheongnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2027-07-11 |
| Hyundai Steel Company | Dangjin-si, Chungcheongnam-do, Incheon, Pohang-si, Gyeongsangbuk-do | MO QSC | 3 | 2028-03-06 |
| Hyunjin Materials Co., Ltd. · | Gangseo-Gu, Busan | MO QSC | 1 | 2017-03-28 |
| Hyunwoo Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2027-06-26 |
| I-PLANT, LIMITED · | Ulju-gun, Ulsan | S Boiler; U Boiler | 2 | 2028-08-27 |
| IBEX MEDICAL SYSTEMS Co., Ltd. · | Wonju-si, Gangwon-do | U Boiler; U2 Boiler | 2 | 2028-09-10 |
| ILJIN Energy Co., Ltd. · | Ulsan | S Boiler; T Boiler; U Boiler; U2 Boiler | 4 | 2027-03-22 |
| ILJIN Energy Co.,Ltd. · | Ulsan | S Boiler; T Boiler; U Boiler; U2 Boiler | 4 | 2027-06-14 |
| ILJIN MACHINERY CO.,LTD. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2028-04-23 |
| ILJIN MTS Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-05-01 |
| ILJIN Power Co., Ltd. | Ulju-gun, Ulsan, Ulsan | N Nuclear; N3 Nuclear; NA Nuclear; NPT Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 8 | 2027-06-18 |
| ILJIN Tech Co.,Ltd. · | Ulsan | U2 Boiler | 1 | 2026-05-26 |
| Ilshin Autoclave Co., Ltd. | Daejeon-si | S Boiler; U Boiler; U2 Boiler; U3 Boiler | 4 | 2027-04-09 |
| Ilshin Valve Co., Ltd. · | Siheung-Si, Gyeonggi-Do | N Nuclear; NPT Nuclear | 2 | 2018-12-30 |
| ILSUNG HISCO Ltd. | Ulju-gun, Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-12-04 |
| IMI Critical Engineering Korea · | Paju-si, Gyeonggi-do | N Nuclear; NPT Nuclear; S Boiler | 3 | 2029-06-23 |
| Industrial Technologies & Services Korea Co., Ltd. · | Busan | U Boiler | 1 | 2027-09-30 |
| INHEUNG Industries Co., Ltd. · | Gyeongju-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-02-23 |
| INT TECH Co., Ltd. · | Chilgok-gun | U Boiler | 1 | 2027-01-16 |
| J SYSTEM Co., Ltd. · | Cheonan-si, Chungcheongnam-do | U Boiler | 1 | 2027-09-17 |
| J.Won Metal Co., Ltd. · | Siheung-si, Gyeonggi-do | BPE BPE | 1 | 2031-05-05 |
| Jangwoo Machinery Co., Ltd. | Busan | U Boiler | 1 | 2028-07-21 |
| JEIL M&S Co., Ltd. · | Icheon-si, Gyeonggi-do | U Boiler | 1 | 2026-11-21 |
| JEIO Co., Ltd. · | Gyeonggi-do | U Boiler | 1 | 2025-10-14 |
| Jeongwoo Industrial Machine Co., Ltd | Cheonan-si, Chungcheongnam-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-07-13 |
| Jeongwoo Industrial Machine Co., Ltd. | Cheonan-si, Chungcheongnam-do | N Nuclear; NPT Nuclear; NS Nuclear | 3 | 2029-08-18 |
| JEONJIN ENTECH LTD. | Gangseo-gu, Busan | U Boiler; U2 Boiler | 2 | 2026-12-08 |
| JFC Corporation · | Yeoju-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2028-08-21 |
| JI KYUNG Co., Ltd. · | Ulsan | U Boiler; U2 Boiler | 2 | 2027-07-08 |
| JINYANG INDUSTRY CO., LTD. · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2028-01-21 |
| JOKWANG I.L.I. CO., LTD. | Yangsan-si, Gyeongsangnam-do | UV Boiler; V Boiler | 2 | 2027-03-14 |
| JOONG WON ENGINEERING & CONSTRUCTION CO., LTD. · | Gunsan-si, Jeollabuk-do | S Boiler | 1 | 2028-02-20 |
| Joongang Engineering Co., Ltd. · | Gimpo-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2029-09-26 |
| JP innovation Co., Ltd. | Gyeonggi-do | PP Boiler; S Boiler; U Boiler; U2 Boiler; U3 Boiler | 5 | 2029-01-13 |
| JUNGANG ENGINEERING · | Yeosu-si, Jeollanam-do | S Boiler; U Boiler | 2 | 2028-07-25 |
| Junghyun Plant Co., Ltd. | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2026-12-14 |
| Jungwoo ENE Co., Ltd. · | Busan | PP Boiler; S Boiler; U Boiler | 3 | 2027-05-21 |
| Jungwoo Precision & Industry Co.,Ltd. | Wanju-Gun, Jeollabuk-do | U Boiler | 1 | 2017-12-09 |
| Juwon Industry Company · | Busan | S Boiler; U Boiler | 2 | 2027-04-01 |
| JYT Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2017-05-28 |
| K FIVE ENG INC · | Jinju-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2029-02-24 |
| K Tech Co., Ltd. · | DangJin-si, Chungcheongnam-do | S Boiler; U Boiler | 2 | 2029-02-28 |
| KAI LABS Co., Ltd. · | Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2029-04-17 |
| Kaichi Korea Co., Ltd. · | Busan | PP Boiler; PRT Boiler; S Boiler; U Boiler | 4 | 2027-05-31 |
| KANG WON N.T.S. CO., LTD. | Dangjin-si, Chungcheongnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2026-11-30 |
| Kangrim Heavy Industries Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | H2 Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2029-06-02 |
| Kangrim Heavy Industries Co.,Ltd. · | Changwon-si, Gyeongsangnam-do | H2 Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2026-11-18 |
| KANGWON ENERGY CO., LTD. | Gunsan-si, Jeollabuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-12-16 |
| KANGWON N.T.S. CO., LTD. | Dangjin-si, Chungcheongnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-10-29 |
| KARAM CO.,LTD · | Chanwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-04-27 |
| KD TECH Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2026-12-18 |
| KDM TECH LTD. | Ulsan | S Boiler; U Boiler; U2 Boiler | 3 | 2027-10-06 |
| KEOSAN PnF Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2019-01-22 |
| Keowha Co., Ltd. · | Incheon | S Boiler; U Boiler | 2 | 2028-02-20 |
| KEPCO Engineering & Construction Company, Inc. · | Gimcheon-si, Gyeongsangbuk-do | N Nuclear | 1 | 2029-02-11 |
| Keumsung Hightech Co., Ltd. · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2028-06-05 |
| Key Valve Technologies Ltd. | Siheung-si, Gyeonggi-do | PP Boiler; S Boiler | 2 | 2026-10-25 |
| KHAN P&S Co., Ltd. · | Jinju-si Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-11-26 |
| KHB Tech Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-02-11 |
| KHPT Co., Ltd. Yulchon Factory · | Jeollanam-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2027-10-15 |
| Kiturami Co., Ltd. Asan Plant · | Asan-si, Chungcheongnam-do | H2 Boiler; HLW Boiler | 2 | 2028-05-20 |
| KJ Boiler Co., Ltd. · | Hwaseong-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-07-21 |
| KJF Co., Ltd. · | Busan | S Boiler; U Boiler | 2 | 2027-12-15 |
| KLES Inc. · | Daejeon | NS Nuclear | 1 | 2019-01-15 |
| KOBELCO MACHINERY KOREA CO., LTD. · | Busan | S Boiler; U Boiler | 2 | 2028-07-21 |
| KOINS CO., LTD. · | Yeosu-si, Jeollanam-do | PP Boiler; U Boiler; U2 Boiler | 3 | 2017-08-12 |
| KOKS Group Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-07-31 |
| KOLON EN-SOLUTION CO., LTD · | Hwaseong-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-12-03 |
| Korea Authorized Inspection & Research Institute Co., Ltd. · | Seoul | AIA AIA | 1 | 2029-04-11 |
| Korea Special Metal Co., Ltd. | Incheon | UV Boiler | 1 | 2028-03-23 |
| KUKJE Plant Co., Ltd. · | Ulju-gun, Ulsan | PP Boiler; S Boiler; U Boiler | 5 | 2026-02-25 |
| KUMHWA ENGINEERING Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2029-09-29 |
| KUMHWA INDUSTRY CO. · | Danwon-gu, Ansan-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2029-01-30 |
| KumKang Precision Co. Dadae Factory · | Busan | PP Boiler; S Boiler; U Boiler | 3 | 2017-12-19 |
| KUMNAM B&E CO., LTD. · | Hwaseong-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2017-12-29 |
| Kumwoo Ind. Machinery Co., Ltd. · | Jinju-si | PP Boiler; S Boiler; U Boiler | 3 | 2017-07-22 |
| Kunja Chemical Machinery Co., Ltd. · | Ansan-Si | PP Boiler; S Boiler; U Boiler | 3 | 2016-11-01 |
| Kwang Jin Engineering Co., Ltd · | Gimhae-City, Gyeongnam | PP Boiler; S Boiler; U Boiler | 3 | 2016-07-30 |
| KwangLim E&C Co., Ltd. · | Ulsan | S Boiler; U Boiler | 2 | 2016-10-21 |
| KwangShin Machine Ind. Co., Ltd. | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2028-01-25 |
| Kyeam Technologies Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2027-04-12 |
| KyeongHeung Pipe Unit Manufacturing Co., Ltd · | Gyeongju-si, Gyeongsangbuk-do | PP Boiler | 1 | 2016-11-08 |
| Kyung Sung Precision Machinery Co., Ltd. | Gangseo-gu, Busan | NA Nuclear; NPT Nuclear; NS Nuclear | 3 | 2027-06-22 |
| Kyungan Thermotech Co., Ltd. · | Gyeonggi-do | U Boiler; UM Boiler | 2 | 2027-12-13 |
| KyungDong Everon Co., Ltd. · | Pyeongtaek-si, Gyeonggi-do | H2 Boiler; HLW Boiler | 2 | 2029-06-02 |
| Kyungdong Navien Co., Ltd. | Pyeongtaek-si, Gyeonggi-do | H2 Boiler; HLW Boiler | 2 | 2029-02-10 |
| Kyunghan Co., Ltd. · | Gyeongsan-si, Gyeongsangbuk-do | U Boiler | 1 | 2026-10-29 |
| Kyungsung Industry Co., Ltd. · | Gimhae-si, Gyeongnam | PP Boiler; U Boiler | 2 | 2016-11-08 |
| Lees Corporation · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2026-12-14 |
| LG Electronics, AE Division Chiller Business Team | Wanju-gun, Jeollabuk-do | N Nuclear; NPT Nuclear | 2 | 2017-11-07 |
| LG Electronics, Inc. | Pyeongtaek-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2027-01-10 |
| LHE Co., Ltd. | Gimhae-si, Gyeongsangnam-do | U Boiler | 1 | 2029-01-11 |
| LOTTE Engineering & Construction Co., Ltd. | Seoul | NA Nuclear; NPT Nuclear; NS Nuclear | 3 | 2017-03-04 |
| LS ENGINEERING CO., LTD. · | Geumsan-gun, Chungcheongnam-do | S Boiler; U Boiler | 2 | 2027-07-15 |
| M.T. Korea Co., Ltd. · | Busan | PP Boiler; U Boiler; U2 Boiler | 3 | 2017-09-02 |
| Machinery New Core Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2018-02-04 |
| Main Co., Ltd. · | Haman-gun, Gyeongsangnam-do | U Boiler | 1 | 2027-10-20 |
| MCI Co., Ltd. · | Haman-gun, Gyeongsangnam-do | PP Boiler; U Boiler | 2 | 2026-05-26 |
| Megaflexon Co., Ltd. · | Gimpo-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2027-08-13 |
| MF Tech Co.,Ltd. · | Ansan-si, Gyeonggi-do | U Boiler | 1 | 2026-12-06 |
| MiCo HighTech Co., Ltd. · | Incheon-si | U Boiler; U2 Boiler; U3 Boiler | 3 | 2027-06-20 |
| Microsys Co., Ltd. · | Gyeonggi-do | U Boiler | 1 | 2027-04-23 |
| MIKWANG PLANT Co., Ltd. · | Siheung-si, Gyeonggi-do | U Boiler | 1 | 2027-01-08 |
| MIRACLE SOLUTION CO., LTD. · | Daegu-si | PP Boiler; U Boiler | 2 | 2027-04-22 |
| MJ TSR Co., Ltd. | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2027-02-20 |
| Mokyang Technology Inc. · | Suncheon-si, Jeollanam-do | U Boiler | 1 | 2027-07-26 |
| Moo Jin Kee Yeon Co., Ltd. · | Gwangju, Jeollanam-do | N Nuclear; N3 Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 8 | 2026-07-12 |
| MoPEC Co., Ltd. | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2027-02-08 |
| MS ENG Co.,Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2026-12-01 |
| MS ENG Corporation · | Gunsan-si, Jeollabuk-do | PP Boiler; U Boiler | 2 | 2028-05-27 |
| Mt.H Control Valves Co., Ltd. | Gangseo-gu, Busan | UV Boiler | 1 | 2027-11-18 |
| MUYU PLANT Co., Ltd. · | Dangjin-si, Chungcheongnam-do | U Boiler | 1 | 2028-03-18 |
| Mycom Korea Co., Ltd. | Changwon-si, Gyeongsangnam-do | U Boiler | 1 | 2029-07-07 |
| Myeong Jeong Plant Co., Ltd. | Dangjin-si, Chungcheongnam-do | U Boiler | 1 | 2028-12-17 |
| Mytec Co., Ltd. | Gangseo-gu, Busan | S Boiler; U Boiler; U2 Boiler | 3 | 2028-04-28 |
| Myungjin Engineering Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2017-12-05 |
| MyungSung TNS Co., Ltd. · | Daegu | U Boiler | 1 | 2025-03-29 |
| NARB&T · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2028-09-29 |
| National Oilwell Varco Korea Co., Ltd. | Ulju-gun, Ulsan | S Boiler; U Boiler; U2 Boiler | 3 | 2018-01-15 |
| Newtems Co., Ltd. · | Haman-Gun, Gyeongsangnam-do | U Boiler | 1 | 2029-05-26 |
| Nikkiso Clean Energy & Industrial Gases Korea Co., Ltd. | Busan | PP Boiler; U2 Boiler | 2 | 2026-06-26 |
| NK Co., Ltd. · | Busan | U Boiler; U2 Boiler | 2 | 2027-09-15 |
| Number One Technology Co.,Ltd. · | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2029-01-23 |
| NURI Co., Ltd. · | Jeollanam-do | U Boiler | 1 | 2025-06-17 |
| O-SUNG PLANT CO., LTD. · | Gimcheon-si, Gyeongsangbuk-do | U Boiler | 1 | 2027-05-03 |
| Ofe Co., Ltd. · | Haman-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2016-08-02 |
| P&S Co., Ltd. · | Jinju-si, Gyeongsangnam-do | PRT Boiler; S Boiler; U Boiler | 3 | 2028-07-15 |
| PANASIA Co., Ltd. | Gimhae-Si, Gyeongsangnam-Do | PP Boiler; S Boiler; U Boiler | 3 | 2016-09-04 |
| PANASIA CO., LTD. | Busan | PP Boiler; S Boiler; U Boiler | 3 | 2027-09-17 |
| PBST Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-11-26 |
| PK Valve & Engineering Co., Ltd. | Changwon-si, Gyeongsangnam-do | N Nuclear; NPT Nuclear | 2 | 2027-06-18 |
| PNL Co., Ltd · | Goseong-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2029-04-20 |
| PNS · | Gimhae-si, Gyeongsangnam-do | U Boiler | 1 | 2029-04-21 |
| POSCO Co., LTD · | Pohang-si, Gyeongsangbuk-do | MO QSC | 1 | 2029-08-24 |
| POSCO Eco & Challenge Co., Ltd. | Incheon | NA Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; S Boiler | 7 | 2028-10-28 |
| POSCO Plantec Co., Ltd. · | Ulsan | S Boiler; U Boiler; U2 Boiler | 9 | 2017-12-17 |
| Power HX Tech Co., Ltd. · | Ulju-Gun, Ulsan | S Boiler; U Boiler | 2 | 2029-09-29 |
| POWER MnC Co., Ltd | Ulju-gun, Ulsan | PP Boiler; U Boiler | 2 | 2025-08-05 |
| PROCON ENGINEERING Co., Ltd. · | Siheung-si, Gyeonggi-do | U Boiler | 1 | 2027-06-18 |
| PSC Corporation · | Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-08-09 |
| PTK Co., Ltd. · | Hwaseong-Si, Gyeonggi-Do | U Boiler; U2 Boiler | 2 | 2027-10-18 |
| Pusan Internal Tec. & Punching Co., Ltd. | Busan | PP Boiler; U Boiler | 2 | 2029-06-13 |
| PWK Co., Ltd. · | Goyang-si, Gyeonggi-do | H2 Boiler; HLW Boiler; U Boiler | 3 | 2027-12-16 |
| REF KOREA CO., LTD. · | Busan | U Boiler | 1 | 2029-03-13 |
| RES CORPORATION · | Gimhae-si, Gyeongsangnam-do | NPT Nuclear; NS Nuclear | 2 | 2029-06-01 |
| RMK Co., Ltd. · | Miryang-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2016-07-24 |
| Run Tech Corporation · | Busan | U Boiler | 1 | 2027-12-11 |
| S&DKOREA Co., Ltd. · | Siheung-si | U Boiler | 1 | 2029-07-14 |
| S-Tank Engineering Co., Ltd. | Gyeongsangnam-Do | U Boiler; U2 Boiler | 2 | 2027-05-31 |
| SAM JIN PLANTEC Co., Ltd. · | Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2029-09-08 |
| Sam Kyung ENC Co., Ltd. · | Chungcheongnam-do | S Boiler; U Boiler | 2 | 2027-12-24 |
| SAM YEON ENGINEERING CO., LTD. · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2029-05-18 |
| Samchang Advanced Solution Co., Ltd. · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-11-16 |
| SamHong Arcturion Co., Ltd. · | Changwon-si, Gyeongsangnam-do | NA Nuclear; NPT Nuclear; NS Nuclear | 3 | 2029-01-24 |
| Samhwa Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler | 1 | 2029-02-28 |
| SAMHWA Mixing Tech. Co., Ltd. · | Incheon | U Boiler | 1 | 2029-09-14 |
| Samil Co., Ltd. · | Gyeongju-si, Gyeongsangbuk-do | PP Boiler; S Boiler | 2 | 2017-12-12 |
| Samil Industry Co., Ltd. · | Incheon | PP Boiler; S Boiler; U Boiler | 3 | 2028-06-21 |
| Samjung Boiler Ind. Co., Ltd. | Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2029-07-29 |
| SAMJUNG E&W CO., LTD. · | Changwon-city, Gyeongnam | PP Boiler; S Boiler; U Boiler | 3 | 2016-09-04 |
| SAMO DT Co., Ltd. · | Daegu | U Boiler | 1 | 2026-12-21 |
| Samshin Co., Ltd. · | Gunsan-si, Jeollabuk-do, Pohang-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 4 | 2027-07-31 |
| Samshin Limited · | Cheonan-si, Chungcheongnam-do | N Nuclear; NPT Nuclear; NV Nuclear | 3 | 2029-04-03 |
| Samsung C&T Corporation · | Gangdong-gu, Seoul | N Nuclear; NA Nuclear; NPT Nuclear | 3 | 2028-09-02 |
| SAMSUNG E&A CO., LTD. · | Seoul | PP Boiler; S Boiler | 2 | 2028-01-15 |
| Samwhan Machinery Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2028-01-20 |
| SAMWON ENGINEERING Co., Ltd. · | Incheon | S Boiler; U Boiler | 2 | 2026-12-05 |
| SAMWOO ECO Co., Ltd. · | Gwangyang-si, Jeollanam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-07-14 |
| Samyang Entech Co., Ltd. · | Bucheon-City, Gyeonggi-Do | U Boiler | 1 | 2016-11-13 |
| SeAH Besteel Corporation · | Gunsan-si, Jeollabuk-do | N Nuclear; N3 Nuclear; NPT Nuclear; NS Nuclear | 4 | 2029-08-05 |
| Sechang M.I. Co., Ltd. · | Hwaseong-si, Gyeonggi-do | S Boiler; U Boiler; U2 Boiler | 3 | 2028-06-10 |
| Sedae Enertech Co., Ltd. · | Changwon-si, Gyeongsangnam-do, Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 5 | 2018-10-26 |
| Sedae Enertech Co., Ltd. (SEC-GS) · | Gunsan-si, Jeollabuk-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2017-01-11 |
| Sedae Enertech Co., Ltd. (SEC-I) · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2017-01-11 |
| Sedae Enertech Co., Ltd. (SEC-II) · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2017-01-11 |
| SEHWA INDUSTRY Co., Ltd. · | Jeollanam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-07-21 |
| Sehwa MP Co., Ltd · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2017-05-28 |
| SEJIN HEAVY INDUSTRIES Co., Ltd. | Ulsan | U Boiler; U2 Boiler | 2 | 2027-04-09 |
| Sejin Hi-Tech Co., Ltd. · | Gyeongsangnam-do | PP Boiler; U Boiler | 2 | 2016-11-01 |
| Sejin Industry Co., Ltd. · | Gyeongsangnam-do | PP Boiler; U Boiler | 2 | 2017-01-30 |
| Sejong Corporation · | Incheon | A Boiler | 1 | 2017-12-07 |
| SEJONG TECH. CO., LTD. · | Busan | PP Boiler; S Boiler; U Boiler | 3 | 2027-07-19 |
| SEKWANG Co., Ltd. · | Gimpo-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2029-01-26 |
| Sekwang Engineering Co., Ltd. (SKE) (HAS TERMINATED CERTS FROM 2017; REFERENCE ID 107540) · | Gimpo-si, Gyeonggi-Do | S Boiler; U Boiler | 2 | 2017-02-25 |
| Seonghwa Industrial Co., Ltd. · | Jinju-si, Gyeongsangnam-do | PP Boiler; S Boiler | 2 | 2028-06-04 |
| SEOUL MACHINERY CO., LTD. | Dangjin-si, Chungcheongnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2027-05-07 |
| SEST Co., Ltd. · | Busan | U Boiler | 1 | 2029-05-15 |
| SEUNG JIN Engineering Co., Ltd. · | Jeollanam-do | S Boiler; U Boiler | 2 | 2028-11-16 |
| SeungWoo Machine & Construction Co.,Ltd · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2018-01-16 |
| SEWON E&C CO., LTD. | Changwon-si, Gyeonsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2029-08-25 |
| Seyang Corporation · | Siheung-si, Gyeonggi-do | U Boiler | 1 | 2028-04-07 |
| Seyoung Industry Co., Ltd. · | Pohang-si, Gyeongsangbuk-Do | PP Boiler | 1 | 2025-11-12 |
| SHI Co., Ltd. · | Gyeongsangnam-Do | S Boiler; U Boiler; U2 Boiler | 3 | 2016-07-31 |
| SHI Co., Ltd. Haman Plant · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2016-07-31 |
| SHIN GWANG ENG Co.,Ltd. (S.G.E) · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-01-20 |
| Shin Hwa M-Tech Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 6 | 2028-04-29 |
| SHIN SUNG TECH CO.,LTD. | Asan-si, Chungcheongnam-do | S Boiler; U Boiler | 2 | 2017-06-02 |
| Shindo Eng. Lab., Ltd. · | Geumcheon-gu, Seoul | U Boiler | 1 | 2018-02-09 |
| Shindo Heat Exchanger Co., Ltd. | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2029-06-25 |
| Shinhan Engineering Co., Ltd | Siheung-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2029-04-12 |
| Shinhan Heat Exchanger Ind. Co. · | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2018-07-15 |
| SHINSEONG PLANT CO., LTD. · | Gwangyang-si, Jeollanam-do | S Boiler; U Boiler | 2 | 2025-09-16 |
| Shinseung Heavy Industries & Construction Co., Ltd. · | Gwangyang-si,Jeollanam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-07-21 |
| Shinwoo Heavy Industries Co., Ltd. · | Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2018-02-20 |
| Shinyang Corporation · | Ansan-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2017-02-24 |
| ShinYoung Industrial Machinery Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-03-21 |
| SIC Corporation · | Gyeongju-si, Gyeongsangbuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-01-19 |
| SIN SUNG ENG · | Busan | PRT Boiler; U Boiler | 3 | 2026-11-13 |
| SINIL INDUSTRIAL CO., LTD. · | Hwaseong-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-08-15 |
| SINKANG IND. MACH. CO., LTD. · | Gimpo-si, Gyeonggi-do | U Boiler | 1 | 2018-03-04 |
| SJ PLANT CO., LTD. · | Hwaseong-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler | 3 | 2016-12-17 |
| SJM Co., Ltd. | Gyeonggi-do | U Boiler; U2 Boiler | 2 | 2028-11-18 |
| SK ecoengineering Co., Ltd. · | Seoul | PP Boiler | 1 | 2026-04-28 |
| SK Engineering & Construction Co., Ltd. · | Seoul | NA Nuclear; NPT Nuclear | 2 | 2017-11-25 |
| SNT Energy | Changwon-si, Gyeongsangnam-do, Gunsan-Si, Jeollabuk-Do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 7 | 2029-06-27 |
| SNT Energy Co., Ltd. | Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-07-15 |
| Soobo Industrial Co., Ltd. · | Haman-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-09-30 |
| SPICO Corporation | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2027-11-12 |
| SPP Yulchon Energy Co., Ltd · | Suncheon-si, Jeollanam-do | MO QSC | 1 | 2018-01-13 |
| SRC Corporation Ltd. · | Ansan-si, Gyeonggi-do | U Boiler | 1 | 2027-11-02 |
| STA Products Co., Ltd. | Asan-si, Chungcheongnam-do | PP Boiler; U Boiler | 2 | 2018-03-04 |
| Steel Flower Co.,Ltd. Pohang Factory · | Pohang-si, Gyeongsangbuk-Do | PP Boiler; S Boiler; U Boiler | 3 | 2018-02-11 |
| SUNG HYUN CO., LTD. · | Gunsan-si | PP Boiler; S Boiler; U Boiler | 3 | 2029-02-11 |
| Sung Il Co., Ltd (SIM) · | Haman-gun, Gyeongsangnam-do | PP Boiler; S Boiler | 2 | 2019-01-29 |
| Sung Il Co., Ltd. (SIM) · | Gunbuk-myeon, Haman-gun, Gyeongsangnam-do, Haman-gun, Gyeongsangnam-do | NA Nuclear; NPT Nuclear; PP Boiler; S Boiler | 6 | 2028-07-01 |
| Sunghantec Co., Ltd. · | Ulju-gun, Ulsan | S Boiler; U Boiler | 2 | 2027-04-26 |
| Sungkwang Bend Co., Ltd. | Gangseo-gu, Busan | NPT Nuclear | 1 | 2019-02-06 |
| Sungsan Co., Ltd. · | Chungcheongnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-06-04 |
| SUNKWANG TECHWIN Co., Ltd. · | Changwon-si, Gyeongsangnam-do | NPT Nuclear | 1 | 2027-04-26 |
| SUNPLANT ENGINEERING CO., LTD · | Hwaseong-Si, Gyeonggi-Do | PP Boiler; S Boiler; U Boiler | 3 | 2018-04-23 |
| SVC Inc. · | Gimpo-si, Gyeonggi-do | UV Boiler | 1 | 2029-03-25 |
| SWIC Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2027-06-12 |
| Sysco Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler | 6 | 2017-09-12 |
| SYTcompany Co., Ltd. · | Dalseo-gu, Daegu | U Boiler | 1 | 2027-11-20 |
| Tae Hyung Industrial Co., Ltd. | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2017-04-24 |
| Taechang Eng Co., Ltd. · | Goseong-gun, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2028-02-18 |
| Taegwang Mechatec Co., Ltd · | Changwon-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2018-01-09 |
| TAEIN F&C Co., Ltd. · | Ansan-si, Gyeongi-do | U Boiler | 1 | 2018-04-09 |
| Taein F&C Co., Ltd. · | Ansan-si, Gyeonggi-do | U Boiler | 1 | 2028-04-15 |
| TAEJIN HEAVY INDUSTRY CO., LTD. · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2028-11-16 |
| Taekwang Engineering Co., Ltd. · | Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2016-11-06 |
| Taekyung Heavy Industries Co., Ltd · | Changwon-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2019-01-02 |
| TAEWON Corporation Limited · | Busan | S Boiler; U Boiler | 2 | 2017-08-12 |
| Taewoong Co., Ltd. · | Busan | MO QSC | 1 | 2028-03-26 |
| Taeyang Heavy Ind. Co., Ltd. · | Chungcheongnam-Do | S Boiler; U Boiler | 2 | 2018-10-12 |
| TAIBONG INDUSTRIES INC. · | Incheon | U Boiler | 1 | 2028-10-14 |
| TALENT LNG CO.,LTD. · | Busan | PP Boiler; S Boiler; U Boiler | 3 | 2028-09-17 |
| Technical Korea Co., Ltd. | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2029-02-05 |
| TheEVERONE Co., Ltd. · | Ulju-gun, Ulsan | S Boiler; U Boiler | 2 | 2029-01-27 |
| THI Refrigeration Ltd. · | Gangseo-gu Busan | U Boiler | 1 | 2029-04-01 |
| TK-FUJIKIN CORPORATION | Gangseo-Gu, Busan | N Nuclear; NPT Nuclear | 2 | 2018-04-06 |
| TM TECH Co., Ltd · | Gyeonggi-do | PRT Boiler | 1 | 2027-09-27 |
| TMEC LTD. · | Ulsan | S Boiler; U Boiler; U2 Boiler | 3 | 2028-04-18 |
| TNI Co., Ltd. · | Ulju-gun, Ulsan, Ulsan | N Nuclear; N3 Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 10 | 2028-01-19 |
| Tongil Boiler & Industries Co., Ltd · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2027-09-23 |
| TSI Co., Ltd. · | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2026-12-21 |
| TSM Tech Co., Ltd. · | Ulju-Gun, Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2017-06-13 |
| Turbowin Co., Ltd. · | Cheongju-si, Chungcheongbuk-do | U Boiler | 1 | 2028-11-21 |
| U-won Inc. · | Eumseong-gun, Chungcheongbuk-do | H2 Boiler; HLW Boiler; U Boiler | 3 | 2016-12-09 |
| UBEC Inc. · | Cheongnyang-myeon, Ulju-gun, Ulsan, Ulsan | S Boiler; U Boiler; U2 Boiler | 5 | 2027-12-18 |
| ULP Co., Ltd. | Ulju-gun, Ulsan, Ulsan | N Nuclear; NA Nuclear; NPT Nuclear; NS Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 8 | 2028-11-06 |
| Unex Co., Ltd. · | Gimhae-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler | 3 | 2018-04-09 |
| Union Engineering Co., Ltd. · | Changwon-si, Gyeongsangnam-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2016-11-06 |
| UnisonHKR Co., Ltd. · | Chungcheongnam-do | NPT Nuclear; NS Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler | 6 | 2029-07-24 |
| UNIWEL Corporation · | Ulju-Gun, Ulsan | PP Boiler; S Boiler; U Boiler | 3 | 2029-06-25 |
| UST Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | BPE BPE | 1 | 2030-08-08 |
| Valex Korea Co.,Ltd | Pyeongtack | BPE BPE | 1 | 2030-03-20 |
| Valmax Technology Corporation · | Asan-si, Chungcheongnam-do | U Boiler | 1 | 2028-11-30 |
| VISER Co., Ltd. | Ansan-si, Gyeonggi-do | U Boiler | 1 | 2029-07-27 |
| VITZRONEXTECH Co., Ltd. | Ansan-si, Gyeonggi-do | PP Boiler; U Boiler; U2 Boiler | 3 | 2027-01-12 |
| W&P Co., Ltd. · | Gyeongsangnam-do | U Boiler | 1 | 2027-07-08 |
| Welcron Hantec Co., Ltd. | Hwaseong-si, Gyeonggi-do | U Boiler | 1 | 2027-02-24 |
| Wintech Co., Ltd. · | Ulsan-si | S Boiler; U Boiler | 2 | 2017-05-01 |
| WINTECH Co., Ltd. · | Ulsan | S Boiler; U Boiler | 2 | 2027-01-09 |
| WINWIN MACHINERY Co., Ltd. · | Gimpo-si, Gyeonggi-do | U Boiler; U3 Boiler | 2 | 2028-02-21 |
| WISE Control Inc. · | Siheung-si, Gyeonggi-do | PP Boiler; S Boiler | 2 | 2027-07-23 |
| Wonil T&I Co., Ltd. · | Yeongam-Gun, Jeollanam-Do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2016-07-25 |
| WONIL T&I CO., LTD. · | Gimpo-si, Gyeonggi-do | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2027-12-23 |
| Wonjae Korea Co., Ltd. · | Gunsan-si, Jeonbuk-do | U Boiler | 1 | 2029-09-15 |
| WOO JEONG PLANT CO., LTD. · | Gyeonggi-do | U Boiler | 1 | 2028-04-08 |
| Wookyung Plant Co., Ltd. · | Haman-gun, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2029-01-24 |
| WOORI EMI CO.,Ltd. · | Hwaseong-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2026-12-16 |
| WOOSUNG FLOWTEC Co., Ltd. | Busan | U Boiler | 1 | 2028-06-05 |
| Wooyang HC Co., Ltd. | Pyeongtaek-Si, Gyeonggi-Do, Pyeongtaek-si, Gyeonggi-do | N Nuclear; NA Nuclear; NPT Nuclear; PP Boiler; S Boiler; U Boiler; U2 Boiler; U3 Boiler | 8 | 2026-10-15 |
| Wooyang Industry Co., Ltd. · | Pyeongtaek-si, Gyeonggi-do | U Boiler | 1 | 2027-04-11 |
| World Energy Co., Ltd. · | Mungyeong-si, Gyeongsangbuk-do | U Boiler | 1 | 2028-08-27 |
| WSG Co., Ltd. · | Gijang-Gun, Busan | BPE BPE | 1 | 2027-06-02 |
| Y&S Co., Ltd. · | Sacheon-si, Gyeongsangnam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2017-10-14 |
| YEWON INC. · | Gimcheon-si | PP Boiler; U Boiler | 2 | 2026-02-28 |
| YG TECH CO., LTD. · | Changwon-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2029-05-26 |
| Yonghyun Base Materials Co., Ltd. · | Yangsan-si, Gyeongsangnamdo | MO QSC | 1 | 2017-05-05 |
| YOO JIN Technical Manufacturing & Construction Co., Ltd. · | Haman-Gun, Gyeongsangnam-Do | S Boiler; U Boiler; U2 Boiler | 3 | 2029-05-17 |
| YOOBONG Corporation · | Gyeongsangnam-do | S Boiler | 1 | 2029-09-08 |
| YOOYEONG TECH Co., Ltd. · | Gusan-si, Jeollabuk-do | PP Boiler; S Boiler; U Boiler | 3 | 2017-06-16 |
| YOU-ONE INDUSTRIAL TECHNOLOGY · | Gwangyang-si, Jeollanam-do | S Boiler; U Boiler; U2 Boiler | 3 | 2028-11-12 |
| YoungKwang Co., Ltd. · | Ulsan | PP Boiler; S Boiler; U Boiler; U2 Boiler | 4 | 2028-05-19 |
| Youngsan Heavy Industry Co. Ltd. · | Gimhae-si, Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2017-05-20 |
| YOUNGSEONG CO., LTD. · | Gyeongsangnam-do | S Boiler; U Boiler | 2 | 2027-08-11 |
| YSPE CO., LTD. · | Gangseo-gu, Busan | S Boiler; U Boiler | 2 | 2028-02-25 |
| Yuhantech Co., Ltd. · | Yeosu-si, Jeollanam-do | S Boiler; U Boiler | 2 | 2026-12-12 |
| Yukyung Co., Ltd. · | Gimgae-Si, Gyeongsangnam-Do | PP Boiler; S Boiler; U Boiler | 3 | 2016-08-02 |
| YULWON CO., LTD. · | Paju-si, Gyeonggi-do | S Boiler; U Boiler | 2 | 2016-10-14 |
| Yung Jin Co., Ltd. · | Pohang-si, Gyeongsangbuk-do | S Boiler; U Boiler | 2 | 2018-12-15 |
| Yunsung F&C Co., Ltd. | Anseong-si, Gyeonggi-do | U Boiler | 1 | 2026-12-10 |
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