Description difference between API 6A valve and API 6D valve

Sometimes, customers ask us for API 6A valve, but description is too simple and which lead us to consider API 6D valve. So we consider writing something to show normal description difference between valves belong to two standards.

First, let us see some description of gate valves as below:
1. Gate valve, 4” x 1500lb, forged body, raised face flanged end, Body material: A216 WCB , Gear operated
2. Gate valve, 4-1/16” x 5000psi, forged body, flanged end, DD, PU, PSL3, PR1
We can find that bore size and working pressure is nearly the same. The two gate valves can connection together by their own flange. But they belong to two different standards. Let us explain details from their description one by one.
a. Bore size:
API 6D: from 3”, 4”, 6”, 8” to 60”
API 6A: from 2-1/16”, 3-1/8”, 3-1/16”, 4-1/16” to 7-1/16”.
b. Working pressure
API6D: 150lb, 300lb, 600lb, 900lb, 1500lb, 2500lb.
API 6A: 2000psi, 3000psi, 5000psi, 10,000psi, 15,000psi, 20,000psi.
c. End connection
API 6D: RF flange, RTJ flange or welded
API 6A: flanged connection
d. Body material:
API 6D: Specify detailed material grade.
API 6A: AA, BB, CC, DD, EE, FF, and HH

But there is some special description like choke 2” 300lb, RTJ flange, DD, PU, PSL2, PR1. After confirmation with end user, we manufacture and fabricate this low pressure choke according to API 6A. Sometimes, we make ball valves like such kind way.
After this explanation, we hope we will receive detailed request for valves that we can show our quotation ASAP that we will not bother customer to do some decision.