352LCC vs 350LF2

[maddocks]

I have a client spec that requires a particular valve to be 352LCC, however, the supplier has provided a 350LF2 forged valve (globe valve).

Can anyone enlighten me on the key or critical differences? The line is in dehydrated acid gas service and will be traced and insulated. Valve is 1"-900# ANSI RF, OS&Y, API Trim 12

 

[rneill]

A352LCC is a cast material rated to -45 C whereas A350LF2 is a forged material. A350LF2 can be Class 1 which is also impact tested at -45 C or Class 2 which is not impact tested at -45 (I don't remember the exact number right now).

I would normally consider A350LF2 Class 1 material to be an upgrade to A352LCC material and I myself I issue a material equivalency table with my valve PO's that allows this substitution. I would not accept A350LF2 Class 2 material as a substitute since it is not rated for the same minimum temperature.

A350LF2 material being forged is less likely to contain detrimental defects. As well the chemistry results in a valve body that would provide for better quality welds if weld repairs were required.

 

[rneill]

I guess I should mention that A352LCC material is in materials group 1.2 of ASME B16.34 whereas A350LF2 is in materials group 1.1. Materials group 1.2 has higher pressure ratings than materials group 1.1 and however unlikely, it is possible that this could cause an issue. Very unlikely though since the pipe flanges are almost certainly A350LF2 material anyway.

 

[valvit]

rneill...as you suggest, it is an issue, especially at 200 F, where LCC maintains 1500 psig at 200F and LF2 drops to 1360 psig at 200 F. Often times, pipeline flanges are purchased against MSS SP-44, which permits A350 forged flanges to be used to 1480 psig up to 250 F. This gives valve manufacturers all kind of trouble when a flanged end valve has to be rated for 1480 psig at 150 F or higher.

 

[maddocks]

Thanks for your help. Appreciate the feedback and will stick with the LF2 - it meets my requirements for pressure/temperature.