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Process Piping Design

Of all of the activities associated with the layout and design of petro-chemical plants and their facilities piping design is one of the most challenging, interesting and rewarding.

Piping design is the only engineering design discipline which is required to interact with all of the other engineering disciplines. This means that as well as a basic understanding of the process’ the piping designer has to have a detailed technical knowledge of the structural, civil, electrical and instrumentation groups, their procedures and practices. 

For example it is the Senior Piping Designer who designs the layout of the whole facility, determines the size and layout of each unit and their battery limits and positions all of the equipment in relation to each other, while taking into consideration the equipment spacing for fire or explosion mitigation and the economies of piping runs. During this early design phase the Senior Piping Designer also determines the preliminary size and layout of structures and buildings required to support or contain piping and equipment. 

Later in the design it is the Senior Piping Designer who ‘lays-out’ the fractionation/distillation towers. This involves orientation of the internal trays and down-comers, positioning and orientation of the nozzles, instruments and man-ways, positioning and sizing of the ladders and platforms and supporting and guiding the vertical piping. All this from only a P&ID and tray drawings, there is no process, structural or instrument engineer involvement in these tasks it is all the responsibility of the Senior Piping Designer.

These tasks can only be achieved by an individual with detailed knowledge of the construction, operation and maintenance of the plant and all of its equipment. It also requires knowledge of insurance & client guide lines regarding the layout of equipment in relation to the mitigation of fire and explosion risks. That individual is a Senior Piping Designer, not an engineer, the skills and knowledge required to execute a design to this level can only be acquired through many years of experience, it is this experience that justifies the full title of Senior Plant Layout & Piping Designer.

I have been a Plant Layout & Piping Designer for over 40 years, starting in the UK before moving to Canada. During that time I have witnessed many changes in the tools of our trade. From manual everything to plastic models to last, but definitely not least, the 3D CAD revolution! But while CAD changed the way we achieve our design, and in my opinion gave us vast improvements in accuracy and efficiency, the fundamental deliverables of our business have not changed. Our primary goal is still to produce isometrics for spool fabrication in the most efficient way possible. In 1958 we drew General Arrangements with minimal detail, in 2030 we will be building Electronic 3D Models, but we will still produce Fabrication Isometrics. The tools have changed, the product is the same!

I often feel with all the attention and discussion given to the various 3D software packages out there we have lost touch with the point of what we do and the efficiency of the way we used to do it.

Why, when I zoom into a Navisworks model do I see hold-down bolts on the pumps, cooling vents on motors or even a keyway on an air cooler fan shaft? Just because we now use ‘High Value’ designers that’s no excuse for this time wasting detail.

Why are many engineering companies’ still producing Piping General Arrangement drawings? A 3D rendered model can be used for review and construction. Iso production is an extract from the 3D model with no manual input. The GA is therefore now redundant, even though it too can be an extract from the model, what’s the point?

The point is that we are not thinking efficiently, GAs are produced because………..”well GAs have always been produced”…………since 1958!

So the point of this blog is to discuss some of those things that can bring back some of that efficiency in design that we seem to have lost. I will be providing some procedures, forms and standards. There is no copyright on these documents so please feel free to download and use as you see fit. Hopefully this combination of knowledge and documentation may help re-establish some long forgotten “reasons for everything” in piping.

I am happy to answer emails on design issues but I will not be providing a forum as I believe they can sometimes tangent off subject and spread misinformation. 

For general Piping information, training, forum and jobs I would highly recommend Piping