When ordering WP fittings, besides specifying the quantity, dimensions, and material requirements, you also need to pay attention to the WP fitting grade.
Fitting Classes for WP Grade
For example, the following table shows the description of Fittings Classes for WP Grade when purchasing ASME B366 Wrought Nickel Alloy Pipe Fittings.
|
Class |
Construction |
Nondestructive Examination |
|
S |
Seamless |
None |
|
W |
Welded |
Radiography or Ultrasonic |
|
WX |
Welded |
Radiography |
|
WU |
Welded |
Ultrasonic |
The WP pipe fittings grade can be subdivided into the following four sub-grades:
– WP-S (Wrought Pipe – Standard): Suitable for ordinary industrial applications and meets conventional pressure and temperature requirements.
– WP-W (Wrought Pipe – Wrought): Forged to meet higher pressure and temperature requirements.
– WP-WX (Wrought Pipe – Wrought Extra): Designed for extreme working conditions, including higher pressures and temperatures.
– WP-WU (Wrought Pipe – Wrought Ultra): Suitable for the most demanding application conditions, including extreme pressures, temperatures, and corrosive environments.
Select the proper WP-grade subgrade pipe fittings based on the specific application environment and working conditions. For instance, in a chemical environment with high temperature and pressure, WP-WX or WP-WU-grade fittings may be required.
Pipe fittings of each sub-grade must meet the corresponding standard requirements, such as ASME B16.9 and ASME B16.11, and undergo relevant certification and testing.
If the you do not specify S, W, WX, or WU, we can choose to provide any grade for all grades of WP pipe fittings.
CR (Corrosion Resistant) Grade Fittings
In addition, the ordering information in B336 also mentions that CR grade pipe fittings shall not replace the ordered WP grade pipe fittings, and WP grade can replace CR grade pipe fittings.
So what is CR grade pipe fittings?
CR grade refers to pipe fittings made of materials with high corrosion resistance. These fittings are typically made from high-performance alloys such as Hastelloy, Inconel, or Monel. They are designed to resist harsh chemical environments.
CR grade fittings are manufactured to material specifications, which may include relevant ASTM standards. The manufacturing process involves ensuring that the fittings meet the materials’ mechanical and chemical property requirements.
Corrosion-resistant fittings are tested to verify their performance in corrosive environments. This includes testing for chemical composition, mechanical properties, and corrosion resistance.
When dealing with CR-grade fittings, it’s important to reference the appropriate material and manufacturing standards to ensure that they meet the corrosion resistance and other performance criteria for their intended application.
For example, in ASTM, it is mentioned that CR grade pipe fittings are manufactured by the requirements of MSS SP -43 standard and shall meet specific conditions, such as passing a hydrostatic test and withstanding the rated test pressure specified in the MSS SP-43 standard without failure, leakage, or loss of service reliability.
