The design standards of stop valves vary according to the application field, media characteristics and national/regional specifications. The following are the classification and key points of the main design standards:
1. International general standards ISO series
ISO 15761: Specifies the structure, materials and test requirements of metal stop valves, suitable for general industrial scenarios.
ISO 5208: General method for valve sealing performance testing, requiring leakage rate ≤10^-6 mL/s (Class VI).
API standard
API 6D: Design and manufacture of stop valves for oil and gas pipeline systems, covering pressure test requirements for high temperature and high pressure conditions.
2. Chinese national standards (GB/T)
Core design specifications
GB/T 12235: Core standards for steel stop valves and lift check valves for petroleum, petrochemical and related industries, covering flange connection methods, pressure temperature grades and material selection.
GB/T 12233: Applicable to iron stop valves and lift check valves, standardizing basic structural dimensions and sealing performance tests.
Sub-scenario standards
GB/T 12234: Manufacturing requirements for metal globe valve castings, applicable to high-temperature and high-pressure valve shell molding process quality control.
GB/T 19672: General technical specifications for steel globe valves, emphasizing the valve stem guide structure and stuffing box sealing design.
3. Industry and special application standards
Electric power and chemical industry
ASME B16.34: American standard valve design specifications, suitable for high-parameter working conditions such as nuclear power and supercritical steam, with strict restrictions on valve body thickness and material strength.
BS 5352: British standard steel globe valve design and test standard, emphasizing the valve disc forced sealing structure and cycle life test (≥2000 times).
Connection and test standards
Flange connection: According to GB/T 9112~9124, JB/T 79 and other specifications, flange end dimensions and sealing surface treatment.
Pressure test: GB/T 13927 and GB/T 26480 respectively specify the water pressure and air tightness test processes, simulating actual working conditions to verify the sealing reliability.
4. Material and process requirements
Material selection
Valve bodies are commonly made of carbon steel (WCB), stainless steel (304/316L), and chrome-molybdenum steel (such as F321), which must comply with the strength calculation and casting and forging quality requirements of GB/T 12229 and GB/T 12230.
The sealing surface is welded with Stellite or embedded with PTFE soft seal to ensure durability under high temperature/corrosive media.
Manufacturing process
Forged valves must meet the precision control of JB/T 7746, and cast valves must be subjected to radiographic inspection and heat treatment according to GB/T 12234.
Summary: The design of stop valves must integrate international standards (such as ISO), national standards (such as GB/T 12235) and industry specifications (such as API 6D), optimize the structure, materials and sealing technology according to the medium working conditions, and ensure safety and long-term operation.