1 reply to this topic

[vadi]

Sir,

Equipment callout blocks or Description block in P&I Diagrams will contain Vessel Trim number apart from other details such as :
Operating temperature,
Design temperature,
Design pressure ,
Operating pressure and other relevant information based which equipment being reffered.

Basically what i understand from description is Trim number is only pipe class or spec of the piping used around that equipment or is it instruments mounted around equipment.

If someone can through some light on these issues it will be really helpful:

1)Is Trim number a must have inforamtion on P&I Diagrams or can we do without it.(Assume if there are no rules set by company )
2)what is Trim number ?
3)why it is called trim number ?
4)Why pumps will not be having trim number? Is there any restriction for rotor equipment
5)what is the significance?

Regards
Vadi

[gvdlans]

Looking at your questions:

1) Someone needs to buy these items so this buyer has to be told what pipespec to use (e.g. in order to buy the correct valve type, of the correct pound class and made of the correct material) etc as well as a number for administrative purposes. So I would say a vessel trim is a must have on a P&ID. It is normally added to the P&ID in the EPC phase of a project. Maybe there are alternatives of having it on the P&ID itself, e.g. by putting it on the linelist.

2) It's been some time since I worked on P&IDs as a Process Engineer, but your understanding of the vessel trim appears correct to me. The loose piping items connected to a vessel get a linenumber including pipespec, pound class etc and that is called the vessel trim. You have to think about valves on vents, on drains or level gauges.

3) I am not a native English speaker, but when I look into a dictionary, one of the defintions of trim is: "Exterior ornamentation, such as moldings or framework, on a building or vehicle." With a little bit of fantasy, these loose piping items can be considered exterior ornamentation of the vessel. On the other hand, why is a "pipe" called a "pipe" and why is a "drum" called a "drum"...?

4) In case a pump has loose piping items connected to it (items not provided by the pump vendor) it would require a trim number as well.

5) see answer 1