Please somebody tell me in loop of crued oil line that

Your question does not include any details so it is difficult to give anything but a general answer.
In general ALL high points should have a vent and ALL low points should have a drain.

These vents and drains are for use during hydro-testing of the line. Hydro-testing of the line is required on initial installation and after any modifications. The vents may also be used during start-up after a complete shut-down and draining of the system.

What is included as part of a vent or drain: A lot depends on where the Crude line is. The line may be inside the fence and a part of an operating plant with lots of people around or the Crude line may be outside the fence and part of a cross country pipeline subject to possible theft.

If:
a) the line is inside the fence - Vent and Drain - 3/4" Sock-O-Let, 3/4" Nipple (Plain both ends) , 3/4" Gate Valve, 3/4" Nipple (Thread one end) and 3/4" threaded Cap.

b) the line is outside the fence - Vent and Drain - 3/4" Thread-O-Let and 3/4" threaded Plug

What is the maximum operating temperature of this Crude line?
How long is this line and how many loops are there?

Very explanatory reply Jop..! Thanks for the same.
I understood that when we have a line from point 'A' to point 'B' we need to have a vent on the highest point in the line & a drain at the lowest point in the line.

but I have another relevant query about vents & drains i.e.

When you have shop fabricated lines & we are transporting spool pieces to site & the decision to make the spool pieces / shapes is kept with the fabricator.....in this case how does this affect on the hydrotest vents & drains ?
If the hydrotest need to be carried out at shop for each spool? Do we need to have vents & drains for each spool with the same logic High point vent & low point drain??

kindly advice on the above matter pls..!

1. It is most unusual for piping spools to be hydro-tested by the fab shop. In my time as the Engineering Manager of a Pipe Fabrication Shop we never did it and as far as I know during all of my time ion the Engineering and Design side of things we never did it either. Hydro-testing is normally done in the field after the piping is installed complete with all Field Welds and all valves, gaskets and other assembly items are in place.

2. If, and only if, the shop was required to Hydro-test a fabricated pipe spool then I would advise the shop to determine their own best procedure for doing this including all venting and draining.

Thanks for your quick reply Jop...! It solves my query.....I must say you are very knowledgeable person in Piping which is rare thing to find.

Thanks a ton..!

Hi all,

Correct me if I am wrong.

Lines are tested together with equipment connected. Which also means, the line which is starting with vessel A to vessel B may not have hydrotest vent & drains as the connected equipment will have it & can be used for the required purpose.

Looking forward to any correction as per the discussion we are having on this topic in this forum.

Jop-Pls help.

Abhijit, You wrote:
Lines are tested together with equipment connected. Which also means, the line which is starting with vessel A to vessel B may not have hydrotest vent & drains as the connected equipment will have it & can be used for the required purpose.

So let's consider the situation. "Lines are tested with equipment connected" This means the lines AND the equipment will be tested together. Correct? If this is correct, then there may or may not be any high points or low points in the piping. If there are no high points or low points in the piping then you do not need vents or drains in the piping. This means that the equipment on the high end must have a way to vent out any air in the system. It also means the equipment on the low end must have a way to drain out the hydrotest fluid. This brings us to the equipment. Do they each really have a way to vent and drain the system. Do they also have a way to fill the system?

- Are you really going to test through the equipment?
- If you are not going to test through the equipment then how are you going to isolate the piping from the equipment?
- How are you going to fill the piping with hydrotest fluid?
- What size are these specific lines (connected to the equipment)?

Thank you for the reply Jop.

Let me try & give you more information regarding the same though I myself is not too sure how they are going to do it.
Pls refer to the attached sketch/iso for the line route info connecting two equipment.
What is the ideal way of doing the hydro-test for this line? Do we need hydro test vent & drains?

Jop Wrote-
- Are you really going to test through the equipment?---I am not really sure about it.
- If you are not going to test through the equipment then how are you going to isolate the piping from the equipment?--We have spec. blind at one end but nothing like it on the other end. Then I am not sure what is the means of isolating it from equip?
- How are you going to fill the piping with hydro-test fluid?--If not the test is not together with equip. I think we need to have these High point vent / drains for sure.
- What size are these specific lines (connected to the equipment)?--6"

Looking forward to your feedback on above situation.

Regards,
Abhijit

Abhijit,
Thank you for the sketch. It helps a lot.
The way I see things, you have two options:
Option #1 - Hydrotest the piping on the ground before you install the piping. Get two Blind Flanges and install a valved connection (hole in the BF, O-Let fitting , Nipple and valve) in each Blind Flange. Arrange the piping on the ground so there is only one high point and one low point. Install the valved blind flanges and fill the piping with water and do the test.

Option #2 - Install two small valved outlet connections minimum distance from each end flange of the line. Install the line complete with the Spec Blinds. Use the two new branch connections to fill the line and bleed out as much air as possible. Do the test making allowance for the fact you do not have a completely full line. After the test open the valves to drain out most of the water then open the flanges to remove the Spec Blinds and drain out the rest of the water.

Option#1 sounds great with minimum changes required.
Thank you for your response & now I do understand a bit about the way hydro-testing is done in similar situations.

It is not advisable to do this on the fabricator side because it will take time and effort. Hydro-testing is only done on the field. And it will also be expensive if this will be done by the fabricator, it will require additional fee.
The contractor will have a welding inspector for the fabricated spool