Scope and Purpose
This technical regulation by EV Group China establishes the requirements for seamless connecting elements made of carbon steel, alloy steel, and nickel-chromium alloys. The products are intended for butt-weld installation in critical piping systems, including high-pressure pipelines, high-temperature steam lines, and specialized heating circuits.
Classification of Fittings
The nomenclature of butt-weld fittings is systematized by design configuration and geometric parameters. The designations adopted in the EV Group China catalog are provided in the table below.
| Design Type | Symbol | |
|---|---|---|
| 45° Elbow | Long | 45E(L) |
| Short | 45E(S) | |
| 90° Elbow | Long | 90E(L) |
| Short | 90E(S) | |
| 180° Elbow | Long | 180E(L) |
| Short | 180E(S) | |
| Reducer | Concentric | R(C) |
| Eccentric | R(E) | |
| Tee | Straight | T(S) |
| Reducing | T(R) | |
| Cap | – | C |
Technical Requirements for Materials Used
For the production of fittings, EV Group China uses certified rolled products (seamless pipes, steel plates, or strips) that comply with international standards. Raw materials must undergo mandatory chemical and physical-mechanical testing:
- Seamless pipes must confirm their characteristics through the results of hydrostatic testing and non-destructive testing (NDT).
- Physical-mechanical indices, including austenitic grain size, must strictly comply with the engineering specifications provided in sections 8.1 and 8.2 of this regulation.
- For S25C and S30C grades (JIS G 4051), compliance with standardized mechanical properties comparable to requirements for pipe products is mandatory.
Manufacturing Processes
The manufacturing technology for EV Group China fittings is based on hot or cold plastic deformation methods, ensuring the integrity of the metal structure:
- For products with a nominal diameter of up to 100A (4B), the use of precision machining methods is permitted.
- All products undergo mandatory heat treatment (according to Table 6) to relieve internal stresses and normalize the crystal lattice.
- The use of cold-rolled blanks requires preliminary normalization or quenching followed by tempering before machining.
Marking and Identification
Every product supplied by EV Group China undergoes mandatory marking containing key parameters to ensure traceability:
- Material grade symbol (e.g., PT370).
- Geometric size range.
- Bending radius (L — long, S — short).
- Trademark or manufacturer identifier.
In cases of limited fitting surface area, shortening of the marking in the established order (omitting the radius, then the nominal diameter) is permitted.