PTFE Pump packing (stuffing box) sizing problem 1

[KMP04]

PROBLEM: Unfortunately site has no more 1.5" square PTFE braided packing in stores for their water seal stuffing box, located on one of their hydraulic turbine units.

Shipping is 7-10 days and they need the unit online ASAP. The question is, can we compress 1.25" square braid (in stock) to fit into the 1.5" gap to form a sufficient water seal until the right packing arives on site?

The turbine shaft is 16" dia., rotates at 150rpm & the river water temp would not exceed room temperature. Maximum pressure is aprox. 30psi. My only concern was if the 1.25" packing was not compressed enough, it could loosen and uncoil or simply allow excessive leakage.

Anyone have experience with this kind of application?

Thanks, KMP

 

[unclesyd]

You can flatten it to 1.5" with wooden mallet and form. Don't cut the ring to length until you have flattened it to 1.5".
Cut the ends on bias and pack with the cuts at least 90° apart.
Make sure you seat the packing as you go.
If you are using a lantern ring make sure you used it.
Once you set the packing follower try to turn the shaft as you will probably have several more rings of packing.
A little leak is OK, in fact I like it.

 

[MikeHalloran]

Packing for a shaft that size _should_ leak, at a rate that would fill a standard Navy coffecup in about the time that you could fill it with your own, er, waterspout.

Of course you'd use someone else's coffeecup for both the test and the calibration.

;-)





Mike Halloran
Pembroke Pines, FL, USA

 

[unclesyd]

At my age I would have to take the square root of the time for me to fill the cup to get the right time.

 

[MikeHalloran]

Calibration standards eventually drift out of spec.

Use one that's newer than unclesyd, or me.



Mike Halloran
Pembroke Pines, FL, USA

 

[quark]

I found problems with flattening of wire reinforced packings. If the packing is a teflon /graphited derivatives, then it will fit without problems. Asbestos/ Aramide packings are a bit hard for this sort of job. I would also, strictly, prefer skive joints provided at 90[sup]0[/sup] or 180[sup]0[/sup]apart from ring to ring.

You can also think of insitu packing.

 

[KMP04]

Thankyou everyone for your comments. Packing was installed with leakage kept to an acceptable level!

Regards, KMP

 

[unclesyd]

KMPO4,

hanks for the follow up.

 

[arunmrao]

KMP04

Appreciate your follow up.