Do You Need to Multiply Welded Pipe Allowables by 0.85?
Mechanical Engineering, Pressure Vessel, Heat Exchanger, Risk Management, COMPRESS, Pipe, Piping, Welding, Weld randy bogard Mechanical Engineering, Pressure Vessel, Heat Exchanger, Risk Management, COMPRESS, Pipe, Piping, Welding, Weld randy bogard

Do You Need to Multiply Welded Pipe Allowables by 0.85?

Do you need to multiply welded pipe material allowables by 0.85? 

I get a lot of questions regarding the allowable stresses for various material product forms. The one I’ve been asked about a lot recently is whether or not the allowable stress for welded pipe needs to be multiplied by 0.85.

The answer is, probably not, but it depends. You really need to take a look at the material notes for your welded pipe material in ASME Section II, Part D. This will reveal whether or not the lookup allowable in ASME Section II, Part D has already been multiplied by 0.85. Let’s take a look at a couple of the notes in Table 1A:

G24: This note indicates that the 0.85 has already been applied to the allowable stress. You do not need to multiply the allowable stress by 0.85 again. In this example the allowable stress lookup of 14,600 psi can be used directly in circumferential stress equations. 

W12: This note indicates that the 0.85 has not been applied to the allowable stress. You need to multiply the allowable stress by 0.85 if the welded pipe was created without using filler metal. In this example the lookup of 21,400 psi was multiplied by 0.85 to achieve the 18,190 psi allowable used in the circumferential stress equations. 

The ASME Section II, Part D material notes are not just informational, they can directly affect the allowables you used in stress equations.

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Stop Designing with Deadlegs
Risk Management, Piping, Pipe, Mechanical Engineering, Piping Design randy bogard Risk Management, Piping, Pipe, Mechanical Engineering, Piping Design randy bogard

Stop Designing with Deadlegs

Are you unintentionally adding deadlegs to your piping designs? 

We all have hopes and dreams but your "future expansion” may actually be a major hazard due to the susceptibility of corrosion in these areas. Please be careful with piping headers and branched connections that are intentionally blinded off after construction to prepare for a future expansion. Many times the expansion plan never materializes and the associated deadleg is never properly accounted for in the site’s integrity program. 

What’s wrong with deadlegs? They get hardly any flow and experience higher corrosion rates than the rest of the piping system.

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B16.5 Blind Flanges as Reducers
COMPRESS, Pressure Vessel, Flange, Pipe, Risk Management randy bogard COMPRESS, Pressure Vessel, Flange, Pipe, Risk Management randy bogard

B16.5 Blind Flanges as Reducers

Ever see ASME B16.5 blind flanges as reducers?

Just throw any pipe in a standard ASME B16.5 blind and you’re good-to-go, right? 

No. That “standard” ASME B16.5 blind flange may not be “standard” once you decide to start drilling holes in it. Many times ASME B16.5 blind flanges used as reducers include pipes larger than allowed in B16.5 without a reinforcement calculation. Please make sure your facility has proper documentation for ASME B16.5 blind flanges used as reducers.

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Seamless Pipe with PWHT Designation
Pressure Vessel, Risk Management, Mechanical Engineering, Pipe, Piping, PWHT randy bogard Pressure Vessel, Risk Management, Mechanical Engineering, Pipe, Piping, PWHT randy bogard

Seamless Pipe with PWHT Designation

A Post Weld Heat Treatment (PWHT) designation for Seamless Pipe? Is that crazy?

It may not be standard procedure, but it isn’t crazy. I like to specify PWHT for seamless pipe materials when the pipe specification service calls for PWHT.

Let’s take a look at a common scenario where calling out Post Weld Heat Treatment (PWHT) designation for Seamless Pipe could have saved a big headache. In the example picture a new circuit was added to an existing circuit with a required PWHT designation due to service requirements. Since the seamless pipe did not have a PWHT designation, the welded pipe added during an expansion did not receive the required post weld heat treatment. The new pipe section that did not receive PWHT quickly experienced in-service issues.

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