Dear friends,
At present I am doing support design. For designing of supports whether we have to take hydrotest load or normal sustained load. Please advise on this.

Maniampatti mpkumaresan@technip-coflexip.com

Hello Maniampatti,

Will the piping system(s) need to have additional supports (hangers) installed during the period of time that the hydrostatic testing is being conducted? The answer is maybe. The hydrostatic test loading is one of the load conditions that must be investigated by the responsible piping engineer. The piping engineer will have to be sure that all the piping is well supported such that during the hydrostatic testing (when the piping is filled with the hydro-test medium) there will be NO overstresses due to the additional weight of the hydro-test medium (usually water).

Sometimes, when the process fluid that is to be contained by the piping systems is heavier than the test media, it will not be necessary to provide additional temporary supports. In my experience however, most of the time hydro-testing is done, some temporary supports will be needed. In power plants, steam piping may have to be included in the hydro-test of boilers (after boiler repair) if there are no conveniently located stop valves. In these cases there will be a very large difference in total weight when the pipes are filled with water. It is easy to see that spring hangers will “bottom-out” in this scenario and they (and other supports) might be permanently damaged. And of course with the large increase in live-weight, the piping might also be damaged.

It is the responsibility of the piping engineer to determine if additional temporary supports will be needed and where on the piping system they should be located. Also, if the design of the piping system includes resilient (spring type) hangers, these will have to be “locked” in place vertically (making them effectively “rigid”) during the hydro-test (this is usually just a matter of leaving the “preset stops” or “travel stops” in place (or replacing them) until after the hydro-test is finished). This will prevent (among other problems) excessive vertical deflections that may cause over-loads on strain sensitive terminal equipment (e.g., turbines, vessels, pumps, et. al.). Obviously, since there will be little if any temperature change during the hydro-test the temporary supports will be rigid type. The responsibility for releasing the “travel stops” and disengaging (and perhaps removing) the temporary supports before the systems are placed into operation should be assigned to a very reliable person and an independent “double check” should be done.

The piping engineer should look at the adjacent support structures for suitable places to attach temporary supports and should discuss the loads with the structural engineer. The hydrostatic test loading analysis would then be done (CAESAR II has an easy utility for including water weight) and if necessary the CAESAR II model can be modified to include temporary supports. When it has been determined that the design of temporary supports will preclude over-stresses, it is time to talk to the structural engineer again.

Keep in mind that in some piping systems additional supports are already located at various places to assist in maintenance. These supports may be used temporarily to prevent deflections (sagging) of the piping only when the system is out-of-service (and at ambient temperature) and when valves or other in-line components are removed for maintenance. So these supports could be termed "permanently installed, temporarily used”. These “extra” supports may also be used temporarily during the hydro-test if they are available and in the right places. Just be sure to check that they are not overloaded by the added test medium weight. Also make sure the structures that they are attached to will not be overloaded. We like to say “check the load path - follow each and every support load all the way to the ground”.

So, when the piping systems are to be involved in a hydrostatic test, there WILL ALWAYS BE a number of issues that must be addressed. Sometimes, resolving the issues will not involve a significant amount of work, sometimes it will. But it will always be necessary to understand the “load path”.

Best regards, John.

If you are having problems with tremendous loads, you can inquire and suggest a Pneumatic test.

Regards,

Apart from practical aspects addressed by John Breen, it is also indirectly addressed in the code. Read B31.3-2006, Para 321.1, S302.8, S302.3.8. Just imagine what would happen to a large diameter column overhead vapor line supported from vessel clit subjected to hydrotest, if you don't consider hydrotest load in designing the vessel clit?

Even you must supply hydrotest load seperately to the spring manufacturer. Sometimes they may require to increase rod diameter so that spring can take hydrotest load in locked conditions eventhough the spring can is same.

You may consider removing insulation in hydrotest case because generally hydrotest is performed before insulation is done so that all weld joints are exposed for check.

Tushar,

Unless this is a return to Sam's medical analogy, we normally call them vessel clips.

Alessandro,

I would personally be very wary of recommending a pneumatic test of a large line, given the potential energy storage and explosion risk if there is a failure.

John Breen,
You use the following a lot "The piping engineer should " etc, etc.
Please try to be more specific and qualify this "Piping Engineer."
In my world and the world of many others there are a number of "Engineer" positions in piping.

There is the "Piping Design Engineer" responsible for equipment location, vessel orientation, plant layout, piping routing, pipe supporting, etc.

There is the "Piping Material Engineer" responsible for the development and maintenance of the line class specifications along with all the other specifications related to piping materials, coatings and specialty items.

There is the "Pipe Stress Engineer" responsible for doing the stress analysis on submitted systems to confirm or insure that they are designed and supported properly.

There is the "Lead Piping Engineering" sometimes also called: "Project Piping Engineer" or "Piping Engineering Lead." This person is responsible for the operations and actions of all piping personnel, the execution of the piping on the project along with the quality, schedule and cost of the deliverables.

I assume you mean the "Pipe Stress Engineer"

Well, JOP, that is an interesting point of view.

Maybe that is the basic problem with the engineering "business" now.

In my work, I am responsible for all those issues and I am quite willing to accept the responsibility.

I just noticed the date of the OP - May 25, 2002. Wow, that was a while ago. I guess that means that the "search" function is being used more now and I am glad.

Regards, John

Jop,

My experinece in this business has been that it is always better to poke ones's nose into things that are "the responsibility of others" than to have one's nose poked repeatedly for being assocaited with the design of a system that failed. You may be better at avoiding having your nose poked than I am, though.

My understanding of this business is that blame is assigned to one individual primarily for the protection of the egos of the others. In fact, if the "Piping Design Engineer" made a layout error such that a particular piece of equipment cannot does not have adequate tube pull space, then also the "Piping Engineering Lead" made an error by failing to check the layuout for this. The Mechanical Engineer responsible for the heat exchanger also made an error by faling to provide the information on the required pull space in the first place. The Construction Engineer who reviewed the system for maintainability also made an error by failing to ask where the tube pull area was. The HAZOPS team collectively made an error by failing to notice that a particular piece of equipment was not maintainable. You can doubtless extend the blame to the Site Construction team, and perhaps others.

It is regrettable that most engineering failure investigations seek to place the blame on a single individual. To some extent, this is caused by the old-school mamangement philosophy that mistakes could be explained away by reporting that "the individual responsible is no longer with us." But modern-day business schools understand that the errors are caused by the failure to follow the QA/QC process, and that removal of one individual does not fix the faulty process.

The concept of assigning blame to one individual serves to discourage the otherwise laudable practice of poking one's nose into dark corners. But the most successful projects are the ones where the inquisitive few were not discouraged. I strongly urge you to continue to poke your nose into anything that looks odd to you.

If you are a young engineer, you will both learn faster and acquire a reputation as someone who "goes the extra mile." If you have a moderate amount of experience, your input will be appreciated by your peers, and you will become someone who everyone wants to work with because you keep them out of trouble. (Don't worry if your extra effort is not reciprocated. Your superiors will figure it out pretty quickly. Managers are seldom as dumb as the people who work for them think they are.) If you are an old fart like Mr. Breen and myself, it's your job to know everything about your project, and you're not going to acquire that knowledge without a few bumps and bruises.

I am a real "old" guy
I started in the piping field at Fluor Corp. in 1954.
I retired from Fluor in 1999.
During my career at Fluor I spent time as a:
* Model Maker
* Piping Designer
* Piping Checker
* Unit Piping Design Supervisor
* Project Lead Design Supervisor
* Project Piping Engineering Lead
* Piping Materials Manager
* Piping Department Standards Supervisor
* Project Engineer
* Piping Department Manager
* Piping Field Engineer
* Piping Design Training Instructor

I was away from Fluor for 6 years in the mid-80's.
During those I did the following:
* Software Product Development Manager for 3D Piping Engineering & Design computer software products (like PDS but not PDS)
* Manager of Engineering for a Pipe Fabrication Shop
* Independent Consulting

After retirement (in 1999) My wife and I moved to Florida where I finished and published my book:

"Piping Engineering Leadership for Process Plant Projects"
By: James O. Pennock - Published by: Gulf Publishing
You can find it here:
http://www.amazon.com/gp/product/0884153479/002-0384003-0681610?%5Fencoding=UTF8&s=books&v=glance

When it comes to managing the Piping portion of a project I think I am both knowledgeable and qualified.

the biter bit!!!

Hello again Jop,

I certainly did not mean to question your experience or skill and I apologize if I sounded negative as that was not my intent. I suppose I am guilty of "a rant" about what the profession has become and how (in my experience) people now shy away from responsibility.

When I started in this profession (which was not long AFTER you did) the "chain" of job functions was: Department Manager (he was a senior engineer, had an office and did the department's hiring and firing), Squad Leader (he and all who worked under him worked in the open "drafting room" - there might be 15 or 20 "squads" in each engineering department) Engineer (graduate engineers, maybe 2 or 3 in a squad and “Senior Engineers had qualified for a Professional Engineering license), Checker (maybe 2 or 3 in a squad), and draftsman (ranked as scrubbers (they made changes/corrections to drawings and this was the "entry level" drafting job), tracers (they drew the "background" structures on the drawings and passed them on to the draftsmen), junior draftsmen, draftsmen and senior draftsmen (the "seniors" aspired to be checkers). All newly hired engineers would spend one or two years "on the board" as a draftsman before being given "design work". The "line of responsibility" was in the order described above and it was a vertical organizational structure with complete communication from top to bottom. Every now and again, someone (like me) would attend university at night while working at a drawing board during the day and day-time education was AT LEAST as important as night-time education. In those days, there was no shame in telling someone that you were a draftsman as it was a position of significant responsibility. A piping draftsman was responsible for knowing how to "lay-out" a piping system so that it had enough flexibility to accommodate thermal expansion but not so much that it would become a vibration problem. The draftsman knew how to "spot-in" the support locations (e.g., no cantilevered elbows) and he chose spring hangers without very much oversight from the engineers. The draftsman knew how to "design" a piping system such that it could be maintained (e.g., placing valves close to locations where "temporary supports" could be used when the valve was removed for maintenance). When the draftsman made a "print" of his drawing and took it to the checker for checking it was a matter of pride to get it back "all yellow" with no red (correction) markings. The checked drawing would go to the engineer for review, any needed modification (then back through checking) and finally the drawing would be "signed-off" (and usually "stamped") by the engineer. By "signing-off" the engineer accepted all responsibility but everyone in the "chain of command" felt that they shared that responsibility. It was a rigorous procedure and everybody would learn and take pride in the design.

I began to notice in the mid-1970's that people who worked on drafting boards were highly insulted if they were referred to as "draftsmen" - after all, they were "DESIGNERS" and they insisted upon that title. Sometimes that meant that they graduated from an "institution" with a two year associate degree, but before long the title was assumed by all without "benefit of clergy" (by the way I applaud the Society for Piping Engineers and Designers, SPED, for their piping designer certification program). I notice that now that we have "computer drafting" we also have "modelers", who would be elite "designers". However, it should be known that they all abdicate any responsibility for the design. In fact, the direct line of responsibility for the design has become so convoluted that it is never clear who is responsible for what on any particular contract (or even on any particular “drawing”). THIS I find aberrant and THIS was the nerve that was struck causing my "rant". I would rather step forward and say "I am the piping engineer and I am responsible for everything in the design".

Well, of course, I guess this just shows my age and it would be considered "anti-social" behavior if I worked at one of the large "Design Firms" these days. I would not be promoted if I did not "go with the flow". It is a shame really.

Hmmmmmmmmm, was that another extended "rant"

Regards, John

John,
Thank you for your reply.
We are more alike than we are different.

Please keep up the good work. The new comers of today need people like you.