Key Quality Control for High-pressure Underwater Valves
Jun 15, 2023
Table 1 shows the key quality control in the process of product design, manufacturing and testing for domestic manufacturers of underwater valves.
Table 1 Key quality control of high-pressure underwater valves
Table 1 Key quality control of high-pressure underwater valves
| Items | Content | Control basis |
| 1 | General assembly drawing, design analysis report, review of materials | Respond to requirements for COOEC. |
| 2 | Review and approval of supplier lists for soft seals, forgings and internal parts | Pass the audit of COOEC and customers. |
| 3 | Commencement technical clarification meeting | Respond to requirements for COOEC. |
| 4 | Procedures of welding, qualification reports of welding, non-destructive testing, surfacing, TCC spray, review of coating and FAT test program, determination of test programs of valve stems | Respond to requirements for COOEC. |
| 5 | Testing reports of materials, certificate review of materials | Respond to requirements for COOEC. |
| 6 | Review of quality document of the whole manufacturing process | Respond to requirements for COOEC. |
| 7 | On-site witness of surfacing and inspection | Respond to requirements for COOEC. |
| 8 | On-site witness of TCC spraying and inspection | Respond to requirements for COOEC. |
| 9 | On-site witness of sealing structure tests of valve stems | Conduct 1200 tests, the leakage meets the standard requirement. |
| 10 | On-site witness of valve assembly | Respond to requirements for COOEC. |
| 11 | On-site witness of FAT | Meet requirements for COOEC specifications, standards and data standards. |
5. Risk and control measures
(1) Risk of design
Manufacturers of underwater valves need to complete the structural design of underwater valves, design of components and selection of types and materials, and finite element analysis of limit working condition according to the requirements for detailed design functional specifications and data sheets tosure that all calculation methods are reliable and the calculation process is correct.
(2) Risk of manufacturing
In the manufacturing process of the valve, the underwater valve manufacturer needs to complete the machining of all parts, the surfacing welding of the corrosion-resistant alloy Inconel 625 in the cavity, and the TCC spraying of the ball and the valve seat. Manufacturers should ensure the perfection of pr en ocessing technology, welding technology, and TCC spraying technology; ensure that the processing accuracy of valve parts is performed well; the welding has no defects, and the thickness of Inconel 625 reaches more than 3mm; the bonding force of TCC and the base material reaches more than 70MPa. The thickness reaches 250μm and above; grinding accuracy of balls, plates and valve seats should be performed well.
(3) Risk of assembly
Subsea valve manufacturers should ensure the reliability and implementability of the valve, ensure that the assembly is well performed, and there will be no damage to the soft sealing material.
(4) Risk of tests
During the FAT test of the valve and the 1200-time life test of the valve stem sealing structure (required separately by this project), the subsea valve manufacturer shall ensure that the test procedure meets requirements for specification, and the test results meet requirements for the project.
(5) Risk of control measures
