We are making Body and Bonnet with the material SA-216 Gr.WCB, WCA and WCC for high pressure valve. I am not sure which one is the superior quality of the above three grade.And also which is the superior SA-352 Gr. LCA, LCB & LCC?
Quality level is not the issue, it is strength level for design. The quality remains the same for all three grades. Review the SA-216 specification to become familiar with the WCA-WCC grades in terms of differences in chemical composition and strength. For the SA-352 material specification, the casting grade in this specification refers to applicable minimum (low) design service temperature - not quality level.
As a casting producer, the foundry does not decide the selection of the right grade as they are not competent . It is there in the drawing, please check. Also, if the castings are to be certified by any of the agencies, drawing will have to be approved before being released for production.
WCC grade in SA-216 has got highest yield strength among other that is 40 ksi. Chemical composition stays the same for all the grades except Mn content which is higher in WCB and WCC; 1 and 1.2 respectively versus 0.7 in WCA.
The One Big diffrence between LCA, LCB and LCC the Imapct value
The Impact test Value of LCC is Greater then LCB and LCB impact value is greater then LCA. Then interms of Chemical Composition the difference is Carbon %.
The letter W in WCA, B, C indicates use in warm temperature service. The L in LCA, B, C indicates Low temperature service. Depending on pouring practice, heat treatment and composition selected the W grades can be suitable for temps. down to around -10 to -20F and the L grades must meet impact requirements at either -25F or -50F with the criteria getting tougher(pun intended) as you go from A-B-C.
Anybody know how to perform the following test of the spring as mention in ASME Section III Division 1 NB-3594.9 Spring.
The permanent set of the spring (defined as the difference between the free height and height measured a minimum of 10 min after the spring has been compressed solid three additional times after presetting at room temperature) shall not exceed 0.5% of the free height.
I think this test has been carried only after the heat treatment.