Pipe Slope Verification

[Gwolff]

I am in the process of developing a commissioning plan for a cGMP facility. One of the spec. requirements is to verify the pipe slope of the "qualified" systems. I am looking for information on what would be considered acceptable sampling intervals. Should it be every 10 - 20 - 50 feet? Is there an industry standard for this?

 

[JohnBreen]

Hello,

I do not know of any National Standard (per se) that includes this process. This is generally something that we do per a specific Company's procedure (if that exists).

I like to use a "water level" (comprising a 100 foot length of clear plastic tubing which contains water) to do the job. I also have a set of 8 laser equiped "torpedo levels" that are useful. It will usually take 2 or 3 people working as a team.

I always check the slope from hanger-to-hanger and (when I can get to them) I like to include the length from hangers to the next bend (elbow). The slope should be specified by the design team. At power plants (piping in the steam/water circuit), we typically look for 1/8 inch of "drop" per foot of horizontal length.

Checking at the hangers will give us a chance to note how much hanger adjustment might be neessary to obtain the appropriate slope as we walk the system.

I am sure there are as many other ways to do this task as there are other engineers doing it.

Best Regards, John.

 

[abcmex]

Dear Gwolff
You question is a good one but is more related to the area qualification/validation in cGMP. To start with: which is the goal of the validation, "water for injection" should be more stringent than for example "aqua purificata".
The slope varies from 0.5 to 5% but even in the "Guide to inspection of High Purity Water Systems" from FDA they mention that the pipe should have a slope but they do not specify anything additionally.
At the end for the FDA the results (for example CFU per 100 ml) are more important than the way you reach them (slope and slope check interval). Sorry for not been very specific
RGS

 

[quark]

As suggested by JohnBreen, water level is a good instrument. ISPE (International soceity for pharmaceutical engineers) suggests 1" in 10'. We generally practise it.

Regards,

 

[ptiinc]

Assuming that you can access the pipe and you are checking limited distances, Starett makes a level that can be set to a specific grade. If access is difficult, set up a builders level or laser and grade rod. The laser is the easiest if you have the equipment. Go buy a Lica Disto laser range finder ($200) and place it on the grade rod at the level mark each time you shoot vertically to the pipe. The vertical distance will allow you to calculate the grade without leaving the floor. Obviously you have to measure your horizontal distance as well.