Technical requirements and scope of the ASME B16.9 standard
This standard regulates geometric dimensions, tolerances, acceptance testing methods, and marking rules for factory-made wrought butt-welding fittings. The technical requirements cover a diameter range from NPS 1/2 to NPS 48 (corresponding to DN 15 – DN 1200).
EV Group China supplies fittings manufactured both according to strict standards and based on special drawings and specifications agreed upon with the customer for the implementation of complex engineering projects.
The requirements of the standard do not apply to fittings manufactured using circumferential welds or pipe intersections, nor do they apply to field welding processes. Products such as caps and stub ends are exempt from the specification constraints, provided they fully comply with ASTM standards governing the steel grades used.
It is important to note that the standard uses two systems of measurement (metric and US customary), which are not exact equivalents. Design documentation should adhere to one system to avoid inconsistencies. The nominal pressure rating of a fitting is directly correlated with the wall thickness and the steel grade of the corresponding pipe.
Relationship between nominal diameters NPS and DN for EV Group China fittings:
| DN | NPS |
|---|---|
| 15 | 1/2 |
| 20 | 3/4 |
| 25 | 1 |
| 32 | 1 1/4 |
| 40 | 1 1/2 |
| 50 | 2 |
| 65 | 2 1/2 |
| 80 | 3 |
| 100 | 4 |
Note: for NPS > 4, the calculated value of DN = 25 x NPS.
Classification and marking:
Standard fittings that fully comply with ASME B16.9 are marked with the “WP” prefix. Special designs agreed upon with the customer receive additional suffixes for identification: “S58” (for ASTM A 234, A 403, A 420), “S8” (for ASTM A 815), or “SPLD” (for ASTM B 361, B 363, B 366).
The term “wrought” in the context of EV Group China products implies manufacturing from pipe blanks, sheet metal, or forgings. The use of cast blanks is permitted only upon prior agreement.
Types and design configurations of fittings
- Elbows (45°, 90°, 180°) with normal and short radius.
- Special 3D elbows for systems with specific hydrodynamic requirements.
- Equal and reducing tees and crosses.
- Concentric and eccentric reducers.
- Lap Joint Stub Ends.
- Welded Caps.