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Becht Engineering Blog

In this section of the site contributing authors submit interesting articles relating to the various services, industries and research & development efforts of Becht Engineering.

State Approval of Used or Relocated Pressure Vessels

State Approval of Used or Relocated Pressure Vessels
Achieving “State Special” designation for a pressure vessel can require a fair amount of effort in documentation development.   This process is warranted – for example – when a company wants to move a pressure vessel from one facility for operation in a facility located in another state, or when they purchase a used vessel located in another country or state for use in the United States.   The vessel may or may not have been constructed to the rules of the ASME Boiler and Pressure Vessel Code or ASME Code stamped.   A question that typically arises, “Are there regulations governing the relocation/reuse of such vessels?” The answer is “Yes” and the regulations are found within the state agency, e.g.  the Department of Public Safety, the Department of Labor that has jurisdiction over both the construction of new boilers and pressure vessels, and inspection and repairs of existing equipment.  It is headed by...
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Two Rules-of-Thumb Regarding Piping Systems

Two Rules-of-Thumb Regarding Piping Systems
Have you noticed, looking at the famous ASME B31.1 support spacing Table 121.5, that the spacing between pipe supports is roughly “size + 10”, in other words, the spacing between supports on an 1 inch instrument tubing would be “1 + 10” = 11 ft, while the spacing on a 6 inch line for example would be “6 + 10” = 16 ft. There are of course exceptions, for example, to mention one, supports should be added near concentrated weights such as valves or vertical risers.A simple rule-of-thumb that was pointed-out to me years ago concerns the Class rating of flanges. The working pressure for a B16.5 flange at ambient temperature is approximately 2.4 times the flange Class. For example, the working pressure for a Class 400 flange at 100 F is approximately 2.4 x 400 = 960 psi. Referring to B16.5 for Group 1.1 (carbon steel) we read 990 psi...
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Explosive Failure of Vessels

FAILURE MODE - When an explosion (either a subsonic deflagration, or a supersonic detonation) occurs in a metallic vessel, one of three things can happen:Case 1 – Containment: The vessel can contain the explosion, elastically as if nothing happened, or with plastic bulging.Case 2 – Rupture: The vessel can rupture, without ejecting fragments. The rupture can be a fish-mouth ductile tear, or a more brittle running crack.Case 3 – Fragmentation: The vessel can rupture and fragment. There can be as little as a single fragment, for example when the top of a ground-anchored vessel takes off like a rocket, leaving behind the its anchored bottom, or as many as dozens of fragments of different sizes.PREDICTION - Can we predict which of the three failure modes will take place? In most cases, yes. Let’s explain what we mean by “in most cases”:CONTAINMENT - We can predict analytically (by closed-form solutions) in many...
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ASME B31.3 - Substantive Changes to 2014 Edition

ASME B31.3 - Substantive Changes to 2014 Edition
In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2014 Edition of ASME B31.3, Process Piping.These changes are:Category M Fluid ServiceThe definition was revised in the 2014 edition to provide better guidance on selection of the Category M Fluid Service designation(b) Category M Fluid Service:  A fluid service in which all of the following apply:(1) The fluid is so highly toxic that a single exposure to a very small quantity of the fluid caused by leakage, can produce serious irreversible harm to persons on breathing or bodily contact, even when prompt restorative measures are taken; and(2) If after consideration of piping design, experience, service conditions, and location, the Owner determines that the requirements for Normal Fluid Service do not sufficiently provide the leak tightness required to protect personnel from exposure.Flared laps are...
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Recent Comments
Don Frikken

RE:Use of Maximum value of SL ...

I’m not sure I understand your question, but I will try an explanation and you can ask again if what I say does not help. SL for ... Read More
Sunday, 15 March 2015 11:21
Guest — M. Mistry

RE:RE:Use of Maximum value of ...

Thanks for your prompt response. Your explanation is definitely going to help. But I would have further more questions; Up till no... Read More
Tuesday, 17 March 2015 02:26
Don Frikken

RE:RE:RE:Use of Maximum value ...

When we did these calculations using less sophisticated methods than are available today with the various computer programs, we di... Read More
Saturday, 28 March 2015 11:08
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