Gated valve body thickness difference

[Maxvolonte]

Colleagues greet you again and excuse my insistence. What happen is that I started working in another refinery, and the truth is that I do not like the way they are handling things here. My new doubt, arises because the purchasing department, bought a lot of gate valves from two different manufacturers, one local here in Argentina, and the other KSB of China. It turns out that both valves are trim 5 of 3/4 "S 800 SW, but the local brand, the valve body is a thick as a series # 6000 accessory , when the body of the Chinese valve is almost half as thick, as a series accessory # 3000. My query is, it is this normal, to the thickness variation from a brand or manufacturer to other? It happens that the contractor is using both type of valves in the same prefabricated pipes, same service. Any suggestions will be appreciated.
Attached photos,
Best regards

 

[mk3223]

you may check if these two type of valves meet the Class 800 requirements (as a minimum) of the API-602 Standard.

 

[gerhardl]

The real question is not the wall thickness regarding use and quality.

For smaller valves, as this, one manufacturer may well use as 'standard' a body/valve fully tested for one class also for one or two classes below. Another may use a valve tested exactly to the actual class.

What is best? If everything else is equal, the one approved for the highest class might have a small advantage, but not necessarily. One or the other might have weaker spindel and spindel sealing, uneven accuracy over the serie poor and uneven casting or other drawbacks.

The best quality is proven by factory certification, test of material, production, pressure, leakage and reference from long-term users. The best buy is decided by 'Cost over time': (installing cost plus cost by downtime and change/repair/new valve divided by total lifetime).