Piping Engineering / Design Blog.


Piping Designer - Stress Training

Posted by Antony Thomas at Wednesday, March 11, 2009

Piping Designer Stress Training

What does the piping designer need to know? Piping design is more than just knowing how to turn on the computer, how to find the piping menus and the difference between paper space and model space. So, appropriately, what else does the designer need to know about piping design besides how to connect a piece of pipe to a fitting?

Here is a list of some of the most basic of things that a good piping designer should know. Thinking about every one of these items should be as natural as breathing for a good piping designer.

· Allowable pipe spans – All designer need to know and understand the span capabilities of pipe in the different schedules for a wide variety of common piping materials. When a new project introduces a new material with severely reduced span capabilities; supplemental training may be required.

· Expansion of pipe – All designers must understand that they need to treat a piping system as though it is alive. It has a temperature and that temperature causes it to grow and move. That growth and movement must be allowed for and incorporated in the overall design. Not just of that specific line but for all other lines close by. The process of expansion in a pipe or group of pipes will also exert frictional forces or anchor forces on the pipe supports they come in contact with.

· Routing for flexibility – The piping designer must understand how to route pipe for flexibility. Routing for flexibility can normally be achieved in the most natural routing of the pipeline from its origin to its terminus. Routing for flexibility means (a) do not run a pipe in a straight line from origin to terminus and (b) building flexibility into the pipe routing is far cheaper and more reliable than expansion joints.

· Weight and loads (live loads and dead loads) – The piping designer needs to understand the effects of weight and loading. They need to know and understand that everything has a weight. They need to be able recognize when there is going to be a concentrated load. They need to have access to basic weight tables for all the standard pipe schedules, pipe fittings, flanges, valves for steel pipe. They also need to have the weight tables for other materials or a table of correction factors for these other materials vs. carbon steel. They need to be able to recognize when downward expansion in a piping system is present and is adding live loads to a support or equipment nozzle.

· Equipment piping – The piping designer needs to know the right and the wrong way to pipe up (connect pipe to) different kinds of equipment. This includes pumps, compressors, exchangers, filters or any special equipment to be used on a specific project.

· Vessel piping – The piping designer also needs to understand about the connecting, supporting and guiding of piping attached to vessels (horizontal or vertical) and tanks. They need to know that nozzle loading is important and does have limitations.

· Rack piping – The designer needs to understand that there is a logical approach to the placement of piping in (or on) a pipe rack. It does not matter how wide or how high the rack or what kind of plant, the logic still applies. Starting from one or both outside edges the largest and hottest lines are sequenced in such a manner that allows for the nesting of any required expansion loops. The spacing of the lines must also allow for the bowing effect at the loops caused by the expansion.

· Expansion loops – The designer needs to understand and be able to use simple rules and methods for sizing loops in rack piping. This should include the most common sizes, schedules and materials.

· Cold spring/Pre-spring – Designers should understand the basics rules of cold spring and pre-spring. They need to understand what each one is along with when to and when not to use each.





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