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feed detail engineering bidding p&id pfd datasheet

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#1 Skyline


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Posted 15 May 2018 - 08:24 AM

Hi. I would like to ask something related to the inconsistent information contained in the detail engineering design.

For example: As i reviewed the isometric drawing, i found that several drawings were inconsistent with P&ID and also with bill of quantity. There were several lines that were drawn in the isometric but were not drawn in the P&ID. Some valves and instruments were drawn in the P&ID but weren't drawn in isometric and also weren't included in the BOQ.


In this case (or in any other inconsistency case), which one should i trust? Is there any hierarchy of the document that can be referred to? Or what should i do?

Let's say i can't consult to the document creator to confirm which one is correct.

Hope that someone can help me with this. Thank you very much.

#2 Pilesar


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Posted 15 May 2018 - 01:38 PM

P&ID drawings should be the 'master' document. Isometrics should show all the equipment that is on the P&ID. There may be details on the isometric that are not shown on the P&ID (e.g. drains and vents) that the client may consider normal. If the BOQ is not generated from the isometrics, then what is its source? In general, the documents should be consistent and the engineer who generated the design package should be held to account for inconsistencies. There may be safety implications if the plant is not built as designed, so I would try to get written clarification from the engineer designer. Documents should be marked to reflect 'as built' with appropriate authorized signatures.

#3 Art Montemayor

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Posted 15 May 2018 - 03:46 PM



Depending on what your situation is regarding these P&IDs and Isometrics, your situation could be a very serious and detrimental one.  You simply don’t tell us what the situation is and your role (or responsibility) is in all this:

  • Is this an existing, built and operating unit?
  • Is this a proposed unit presently in the final design stage and subject to your (or someone else) approval?
  • Do you represent the client (or owner) of the unit?  Or do you represent the engineer-designer?
  • Are you located in the USA?
  • What do you mean by “Let's say i can't consult to the document creator to confirm which one is correct”?  Are you the proposed operator of the proposed unit design?  If you have no authority to challenge or critique the existing drawings, why are you reviewing them?  This doesn’t make organizational sense in an engineered and properly managed project.
  • If you are, in fact, the future proposed operator of the unit and have concerns about its successful and safe operation, but have no vested authority to challenge the submitted drawings and contradictory design, then you have a serious, inherited problem facing you.  My recommendation is to separate yourself from such a design.  However, this may not be an option or available to you on a practical basis.
  • If you are the vested authority to not only review, but to approve the design, then what you describe doesn’t make sense.  The design, as depicted on the submitted drawings is not valid and, in fact, is flawed.  This is a potential hotbed of future hazards and dangers for those building or operating the unit.

I fully support what Pilesar has stated and reinforce his very important points of primary importance:

  • The P&ID is the document of “record” in the USA and is treated as such by such government agencies as OSHA and the U.S. Chemical Safety and Hazard Investigation Board.  The P&ID of an operating unit must factually and truthfully represent the “as-built” existing condition of that unit - and that includes drains and vents.  Any equipment or item that could be related to a potential hazard or accident must be accounted for in the P&ID.  That is why it is so important for all operating units to always fully document all Procedures of Change in the unit.  Otherwise, any subsequent Hazop discussions would be a total waste of time done on false information.  That has been my experience with OSHA inspectors.
  • The engineering design and the contractor generating and using the same has to be fully accountable for what is built and operated as per the unit’s P&ID.
  • Any discrepancies between the proposed P&ID and any isometric drawings to be used in the construction are subject to correction(s) and should be indicated in each affected drawing’s data table as a revision to a prior release.
  • This information is not only critical for investigations in the event of future accidents or hazardous incidents, but is also essential for legal procedures and protection.  Insurance companies will surely rely on reviewing all this documentation.

I hope this experience helps you in making the correct and indicated decision regarding these discrepancies.

#4 Skyline


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Posted 16 May 2018 - 01:19 AM

Hai Mr Pilesar and Mr Art Montemayor.


I am sorry that i didn't properly describe the situation and my role.

I represent the owner of the project as an engineer. The detailed engineering documents were created by Consultant and had been reviewed (and approved) by our other division (division A) before being transferred to my division (division B ) for further process (procurement and construction). Unfortunately there was a organizational restructurization and most of the staffs (from division A) who handled the previous process (detailed engineering) were transferred somewhere else.


Now after continuing the process to procurement and construction, the Contractor finds several inconsistency and after contract award they ask for clarification from my division (division B ) before proposing additional cost. My division (division B ) doesn't want to be held responsible for this additional cost and thus ask division A to clarify, but it takes really long time to clarify (they said the documents have been approved, the contract with the Consultant has been settled and they need to pay additional cost to get clarification from the Consultant, etc).


What is the normal practice if after contract closing, the owner finds out that the some of the Consultant's deliverable is incorrect? Should the owner ask the Consultant to fix the deliverable without paying additional cost or is it normal to pay additional cost to fix it?


The additional cost probably relatively low, but right now the cumulative change order has already exceeded our normal tolerance (due to other incomplete/missing scope, etc), and we're already behind the schedule, so my boss ask my division to try fixing it internally together with division A (without Consultant who created those documents).

Edited by Skyline, 16 May 2018 - 01:22 AM.

#5 Pilesar


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Posted 16 May 2018 - 09:20 AM   Best Answer

A few comments:

Inconsistent documentation should never have been approved. The technical term for your situation is a 'mess'.

Someone has to fix the problem. It sounds like the responsibility belongs to your 'division A' since they issued the design package.

The method they use to correct the problem is up to them and not in your domain.

If they get the Consultant involved in fixing the problem, the Consultant will not work without getting additional pay.

There will be extra cost to your Contractor which they will charge to your 'division B'.

Your 'division B' will then try to pass these costs to 'division A'. Internal politics will determine who ultimately pays for the mistakes.

If 'division A' does not accept responsibility, then 'division B' should probably take on the responsibility in the best interests of the company.

In the end, the documentation should be consistent, assessed for safety and performance, and implemented properly in the field.

Someone will pay for the additional cost. 

Typically what happens is that 'division B' will keep track of the additional cost through rigorous documentation and then try to get reimbursed later.

#6 Art Montemayor

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Posted 16 May 2018 - 10:06 AM



First class, engineering consulting advice.  Kudos to you.



You have received top-notch, specific and experienced advice from Pilesar.  All I could add to what he states is personal advice:  You are the owner's representative and responsible for protecting his/her interests and safety.  If no one else takes immediate action(s) such as detailed by Pilesar, you should take a leadership role in correcting this awful situation before it gets worse or creates something everyone will regret.  It may not create a lot of friends for you, but that's what they pay us engineers for.


Good luck on going forward.  (And, oh yes, DOCUMENT everything!)

#7 Skyline


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Posted 17 May 2018 - 01:56 AM

Thank you very much Mr Pilesar and Mr Art Montemayor for the advice.

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