API pump pressure casing connection : flange vs thread

[billbusy]

Per my past experiences, it is normal practice to use threaded connection for seal flush plans in API pumps as per API 610 section 6.4.3.1, it clearly specifies that all auxiliary connection to pressure casing except the SEAL Gland shall be flange connection

my question is why seal gland connection can be threaded? what is the potiential issues if I use threaded connection on the pressure casing for other service (i.e. bearing lubrication)?

thanks


Oil & Gas industry in Canada.

 

[1gibson]

The first connection to the seal has to be threaded, in most cases you won't be able to get it in/out of the pump if there is a flange welded to it.

 

[billbusy]

1gibson
what do you mean, I was thinking API 610 specifies that the connection on the pump casing shall be flanged except in/out seal gland.

Oil & Gas industry in Canada.

 

[1gibson]

Yes, and I was explaining why there is an allowance for threaded connection on the seal gland, which is the question you asked:

"my question is why seal gland connection can be threaded?"

 

[TenPenny]

"my question is why seal gland connection can be threaded? what is the potiential issues if I use threaded connection on the pressure casing for other service (i.e. bearing lubrication)?"

As noted above, the seal gland connection will be threaded because there is no room on the seal gland for a flange.
As to the other question, I don't understand why you would use a connection to the pressure casing for bearing lubrication.

 

[bingopin]

Issues with threaded connections include the reduction of pipe wall thickness caused by the cut threads. To mitigate this issue, our specs call for the threaded piece of pipe to be xxs or Sch. 160. Look at some of your other pumps and I expect you'll see tubing connections to seal glands made with a threaded tubing to pipe fitting.