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.
Becht Engineering staff are experts in piping, and include former chairman of various ASME piping committees, including ASME B31.3. Becht Engineering performs detailed design for complex piping systems including very high temperature and pressure systems such as piping for FCC flue gas expanders and high pressure LDPE systems, as well as design, a...nalysis, troubleshooting and fitness for service evaluation of piping. More

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...
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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 Service The 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...
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Don Frikken

RE:When will the 2014 edition ...

It was issued in February 2015.
Thursday, 07 January 2016 12:45
Don Frikken

2014 Edition Publication Date

The currently scheduled publication date is February 21, 2015.
Monday, 26 January 2015 12:14
Don Frikken

RE:Question

I'm not sure what is meant by "codes exam". B31.3 says it is effective six months after it is published, but a different date can ... Read More
Sunday, 01 February 2015 11:05
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Buried Polyethylene Pipe: An Excellent Choice for Water Service

Buried Polyethylene Pipe: An Excellent Choice for Water Service
Buried steel pipe is prone to pitting due to external (soil-side) corrosion and internal (water-side) corrosion and biofouling. Preventive and mitigative measures include periodic inspection, cleaning, chemical and biocide treatments, and repairs. A cost-effective alternative consists in replacing the buried steel pipe with a non-metallic pipe, in particular high density polyethylene (HDPE). This alternative, widely used for buried waterworks and gas distribution piping, has been used at several nuclear power plants for non-safety related piping. Through ASME Code Case N-755, an alternative is now available for safety-related Class 3 piping. The first industrial polymerization of the ethylene monomer CH2=CH2 into polyethylene (-CH2-CH2-)n dates back to the 1930’s. Today’s polyethylene pipe is designated by its ASTM D 3350 name, such as PE3408 where 3 stands for the cell density, 4 is its resistance to slow crack growth and 08 reflects its hydrostatic design stress at room temperature (allowable stress in service)...
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What is the Future of ASME B31.3, Appendix P?

What is the Future of ASME B31.3, Appendix P?
Appendix P was written to introduce piping flexibility analysis rules that are more suitable for computer piping flexibility analysis, in contrast to the rules in the base Code which were written when piping analysis was done by hand calculations.  Most of the elements of Appendix P have been, or are proposed to be, added to the base Code.  So what does the future hold? The primary reason Appendix P was written was to introduce the concept of taking differences in operating stress states.  This is because there is an interaction between sustained and displacement loads with nonlinear systems.  Supports, for example, can be engaged in one operating condition, and not another, which effects the stress range of the system.  The base Code was written based on looking at stressed due to sustained loads and displacement loads separately.  Although commercial pipe stress software may take differences in operating conditions to determine...
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Chuck Becht

Appendix P

Yes, at the last minute the deletion of Appendix P was implemented. I think all of Appendix P other than the alternative allowabl... Read More
Tuesday, 22 December 2015 14:08
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