| Standard_ID | HG 21505-1992 (HG21505-1992) |
| Description (Translated English) | Combined Sight Glass |
| Sector / Industry | Chemical Industry Industry Standard |
| Classification of Chinese Standard | G91 |
| Classification of International Standard | 71.12 |
| Word Count Estimation | 15,000 |
| Date of Issue | 7/27/1992 |
| Date of Implementation | 12/1/1992 |
| Quoted Standard | GB 3985; GB 1804; HGJ 501; SJ-6 |
| Regulation (derived from) | Industry-Science (2010) No.77 |
| Summary | This standard specifies the combined endoscopic series, design parameters, installation dimensions and technical conditions. This standard applies to the chemical, petroleum, pharmaceutical, light industry, machinery and other sectors, bolted directly on the takeover pipe flange interface or modular endoscopy. |