Differences in standard positioning
| Standard | Nature and scope |
|---|---|
| ASME B16.34 | Basic standards for general valves: covering design pressure-temperature ratings, wall thickness calculations and material selection for flanged, threaded and welded-end valves, applicable to gate, globe and ball valves and other valve types. |
| API 600 | Industry-specific standards: only for the oil and gas industry bolted bonnet steel gate valves, focusing on the structural strength and sealing reliability under heavy duty conditions. |
Key difference: ASME B16.34 is the universal cornerstone of valve design, while API 600 is a special code for gate valves in the petrochemical field.
Comparison of technical requirements
1. Structural design
ASME B16.34:
Specify the minimum wall thickness of the valve body, passage size and other basic parameters, allowing floating stem design;
No mandatory requirements for sealing form (can choose soft seal or metal seal).
API 600:
Mandatory rigid stem (to prevent deformation under high pressure conditions);
Must use metal sealing (seat surfacing carbide, such as Stellite 6) to withstand high temperature particulate media.
2. Pressure testing
| Test items | ASME B16.34 | API 600 |
|---|---|---|
| Shell test | 1.5×PN(water pressure) | 1.5×PN(water pressure) |
| Seal test | 1.1×PN(water pressure) | 2.0×PN(Low pressure airtight + high pressure watertight) |
| Fire Test | not required | Mandatory compliance with API 607 fire resistance standard |
Note: The high pressure sealing test pressure of API 600 is much higher than ASME B16.34 and requires verification of gas tightness.
3. Materials and Manufacturing
ASME B16.34: references ASTM material standards (e.g., A216 WCB), but does not limit specific material grades;
API 600:
Limit the valve body material (must be carbon steel / alloy steel, such as A216 WCC, A352 LCC);
Valve stem must be stainless steel (e.g. A182 F6a);
Requires full bore passage (reduces flow resistance and avoids media deposits).
Application Scenario Comparison
| Standard | Typical applications | Representative working conditions |
|---|---|---|
| ASME B16.34 | General industrial piping (water treatment, HVAC, low pressure steam) | PN≤Class 600, Temperature≤425°C |
| API 600 | Oil/gas pipelines, refineries, high pressure steam systems | PN≥Class 300, sulphur-containing oil and gas, high-temperature particulate media |
TIP: API 600 gate valves typically weigh approximately 20% more than ASME B16.34 valves of the same pressure rating (due to reinforced construction).
The project selection recommendations
Priority selection of API 600:
Gate valves involved in sulphur-containing oil and gas, high-pressure steam (>5MPa) or fire risk areas;
Select ASME B16.34 is sufficient:
Ordinary water/gas media, Class 150~300 low pressure clean pipeline;
Co-operative use:
API 600 valves still need to meet the pressure-temperature rating requirements of ASME B16.34, and the two are complementary rather than substitutes.
Summary: ASME B16.34 is the general rules of valve manufacturing, API 600 is a petrochemical high-risk conditions of the steel gate valve special reinforcement programme, the latter in the Seal level, materials and testing are significantly stricter than the former.
