B.P. Nansi
Piping is an asset for any project. The plant will be as good as the piping layout. Good piping will increase efficiency and bad piping will reduce efficiency. But there is more important effect of bad piping. It can even cause an accident. The plant piping can make or break a plant.
Piping layout is engineering and art. It should ease the operations, help the production and should be pleasant aesthetically. A beautiful piping layout is a plus point to the managers, workers, maintenance crew and the visitors.
The principle for layout design is: plant integrity, operation, maintenance and lifecycle cost. Here are some points for design engineers, project engineers, project managers, piping fabricators and contractors:
n Take input from engineering departments, operations and maintenance personnel
n Follow codes, standards and recommended practices
n Plan the equipment layout for (1) operability, (2) maintenance and also (3) for piping
n All relief pipes, especially steam relief pipe, must release at a distance and at a height, at a safe point. A sudden release of steam can hurt an unaware worker
n Expansion bends, loops and expansion joints will keep pipe stress low. Use them for long run piping
n Stress analysis of all piping systems is a good investment. Stress analysis will bring out proper layout and that will decrease the original cost, save pumping energy and will reduce the maintenance/replacement of pipe
n Location of supports, guides, and anchors is a vital point. Involve your civil engineer at the beginning to give you support structures
n Low points drains and high points vent is an intelligent practice
n Keep all valves accessible for operation
n Keep all gauges, recorders, thermometers etc at the level for easy reading and attending
Pipe openings
Many pipes; viz water supply, raw fluids, fuel gas etc enter a process building and many pipes viz. final product, condensate, cooling water etc leave the process building. Often the entry-exit is through walls. This needs well-defined and well-planned pipe openings. The building is constructed much before the piping contractor comes in. Often, either the pipe openings are not planned or planned bad or forgotten or, later, the piping layout changes. When that happens, take that there is a site crisis.
When piping contractor starts erecting, he finds that there is no opening. Walls are broken. This has happened many times at many places and will happen again. It is one of the commendable points to avoid such situation. Be vigilant.
Interference
This is another big challenge. Interference of a pipe with another pipe or with equipment or with a structure etc is a common scene in many piping layouts. That is because either the piping engineer has 'goofed' or the 'other' things have changed after the piping layout was done. Be careful. A serious issue happens when a pipe, as designed, is going through a beam or a column. This is an embarrassing situation.
What happens is that you can break a wall, but you just can not touch a beam or column. Invariably the piping is changed. That brings in factors of pressure loss, stress analysis and aesthetics. That is why the piping engineer has to be vigilant.
Pump piping
This is a challenge. All centrifugal pumps have NPSH requirements. That has to be given for efficient and safe operation of the pump. The piping layout has to be right. Even after careful evaluation and selection, a centrifugal pump may not operate as expected.
Pipe color codes & ID
When you paint the pipes, follow a color code. Indian Standard defines which colour tells what fluid. For insulated pipes, give colour-coded bends. Then label all pipes to tell what service is inside. Also paint-write line ID numbers on the pipes.
A right piping layout will be cost effective, because it saves money at installation, but saves energy in pumping service. Ensure your project has the right layout
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