Double Block and Bleed Valves

Double block and bleeds are designed for applications where positive isolation is required due to the dangerous nature of the process, and absolute safety is paramount. They are used to isolate the process from equipment that requires service, and will not allow the process through to the technician. These valves are available in a very wide range of configurations, ranging from 1/4-inch NPT to 2500lbs ANSI class flanged, as well as ball valve and needle valve configurations.

Panam double block and bleeds are generally for instrumentation applications, and are used to isolate pressure sensing instrumentation from: poisonous, flammable chemicals; super-heated steam; vaporised hydrocarbons at elevated temperatures; etc… LCO Technologies stock double block and bleeds in 1/2-inch through 1-inch threaded configurations in 316 stainless steel NACE. Flanged configurations and Monoflanges are available with a 4- to 6-week lead time.

Depiction of standard practice
Standard Practice: Weld on a TEE or a Saddle or weld on a Companion Flange
LCO Technologies Solution: Weld in a Thread-o-let or Sock-o-let

Where a flange is called for, the cost of the LCO Technologies 2-bolt inlet flange arrangement is a fraction of the cost of current standard practice, which is to weld a flange onto a tee, or to saddle and flange up the double block and bleed. The standard practice is a very expensive practice.

In the field we are seeing many installations with welded gates or globes with a TEE in the middle and total of 8 welds (see figure 2 for an illustration). Some installations have 150cm long inlet pipes. When asked why the inlet pipe is so long we were told: “So when we have to cut the valves out during turnaround we enough pipe left over for welding in a new DB&B assembly”.


LCO Technologies double block and bleeds with 2-bolt inlet flanges eliminate the need for welders when servicing or replacing the valves. Because our valve can be removed, there is no to include the valve in post-weld heat treating.

LCO Solution Apparatus
Figure 2: Field installed DB&B

For shipping, a simple flange protector can be used for spool pieces that have the inlet flange attached, no damage during shipping. The valve, being separate, is not exposed to field abuse.


  • 316 stainless steel or A105 carbon steel
  • Monel 400, Duplex UNS, or Titanium Grade 2 available on request
  • Built to MSS-SP-99
  • ISO 9000 Certified

Data Sheets:

End Connections Material Model Number
3/4" NPT(M) x 1/2" NPT(F) 316 Stainless Steel PDBB-H-S-128-MF-SG
3/4" NPT(M) x 1/2" NPT(F)
High Temperature
316 Stainless Steel PDBB-H-S-128-MF-HT-SG
3/4" NPT(M) x 1/2" NPT(M)
High Temperature
316 Stainless Steel PDBB-H-S-128-MM-HT-SG
1" NPT(M) x 1/2" NPT(M)
High Temperature
316 Stainless Steel PDBB-H-S-168-MM-HT-SG
1/2" NPT(F) x 1/2" NPT(F) 316 Stainless Steel PDBB-BNB-SS-88-FF
1/2" NPT(F) x 1/2" NPT(F)
High Pressure
316 Stainless Steel PDBB-BNB-SS-88-FF-10K
Monoflange 1/2" NPT(F) x 2" RTJ 300# 316 Stainless Steel PDBB-50-300#-SS-SG
Monoflange 1/2" NPT(F) x 2" RTJ 600# 316 Stainless Steel PDBB-50-600#-SS-SG
Monoflange 1/2" NPT(F) x 2" RTJ 1500# 316 Stainless Steel PDBB-50-1500#-SS-SG
3/4" 150# Flange x 1/2" NPT(F) 316 Stainless Steel PDBB-BBN-SS-20-150-FN
2" 150# Flange x 1/2" NPT(F) 316 Stainless Steel PDBB-BBN-SS-50-150-FN
3/4" 150# Flange x 3/4" 150# Flange 316 Stainless Steel PDBB-BBN-SS-20-150-FF
2" 150# Flange x 2" 150# Flange 316 Stainless Steel PDBB-BBN-SS-50-150-FF
2" 600# Flange x 2" 600# Flange 316 Stainless Steel PDBB-BBN-SS-50-600-FF

Note: Some drawings may be out of date. All products in compliance with ASME B 16.34 (temperature range -50F – 1000F).