friction at line stops and guides

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15 years 10 months ago - 15 years 10 months ago #7339 by alexsel
friction at line stops and guides was created by alexsel
I am workin in a small project organisation .We are presently engineering a small oil and gas separation project.

at the beginning of the project, the client in fast start of the project verbally agreed to the proposal by our stress engineer that friction shall be considered at resting supports and friction at guides and line stops shall not be considered as it is not necessary.

Almost 80% of the engineering is over, client has now appointed a consultant who has instructed us to also include friction at line stops and guides.

our organistaion has strongly objected to this instruction saying that the consultant has looked at the situation from a very conservative and academic point of view . and this will affect our pipe routing due to revised nozzle loads.. Even the loads provided to civil could change and the site contrator shall penalise us since he has already procured and fabricated strutural steel sections as per our calculations.

the client consultant has put his foot down. There is now a stalemate.

can anybody please explain to me how there can be friction at line stops and anchors and which of the two above organisation is correct in their requirement.


awaiting your reply,

regards,
alexsel

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15 years 10 months ago - 15 years 10 months ago #4666 by Jop
Replied by Jop on topic I'm sorry that I can't
I'm sorry that I can't offer any help on the specific Stress aspects of this problem.

However i would like to point out something to everyone who might read this post. You wrote "the client, in fast start of the project verbally agreed to the proposal by our stress engineer."
When will people learn, "If it is not in writing then it does not exist"

At the front end of a project, Fast Track or not, there should be a process called "Scope of Work" development. A "Scope of Work" for any process plant project should be prepared by every Engineering and Design discipline and include two parts.
Part one shall be that discipline's understanding of what plant includes. This is called the Scope of Facilities.
Part two shall be that disciplines understanding of what they will do, how you will do it and what deliverables will be produced. This is called the "Scope of Services".

After the Company Project Manager and the Client agree on it and approve it, it then becomes a part of the Contract.

Source:
"Piping Engineering Leadership for Process Plant Projects"
By: James O. Pennock - Published by: Gulf Publishing.
You can find it here:
www.amazon.com/gp/product/088415 ... s&v=glance

Do it once and Do it Right

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15 years 9 months ago - 15 years 9 months ago #4679 by banerj1s
Replied by banerj1s on topic Alexel, We had this topic as
Alexel,

We had this topic as a major debate of whether to use friction in line stops and guides. The friction factor comes in play when the line moves. Now as soon as the line is charged the line does moves momentarily so considering the friction factor is an conservative approach because there is no friction force when the line come to a stable equilibrium simply because the line doesnt move. You can always argue that the extra loading because of the friction factor wont appear in continuous operating state however static stress analysis is not for a moment force but for continuous service. However it is the contract that has the last say. For something that is not in contract bang the table and say that you would ensure that the design works.
Best of luck!!

Cheers

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