Incident Report

Subject:             Gasket Deformation - Your Views              

Date of Email reporting Incident:   Sun 04/06/2006 20:00

Report Detail:

During an inspection of a client's vessel (cruise ship), an individual from their corporate office commented that he thought the visible deformation of the gaskets in the vessel's fire fighting nozzles was caused by contact with the generous amount of petroleum based lubricant (grease) applied to the threads on the appliances and fire hose (see attached photo). Can you supply any input concerning the validity of this theory?

Responses:

Date

Detail

Documents
Tue 06/06/2006 08:48 The damage looks more like excessive force on the coupling when it has been connected but what age is the gasket as these items are a serviceable part and should be replaced at the yearly service intervals.  
Mon 05/06/2006 11:25
I have seen cases where Viton ( rubber ) O rings were attacked by hydrocarbons ( under special operating conditions and over a long period of time ) . Although I have not seen a case like this before , I would find the theory of excessive greasing plausible.
Excessive greasing can result in several forms of deterioration. it may be the lifetime of the gasket that resulted in this deformation or incorrect jointing .
  
Wed 07/06/2006 16:21

I have come across similar problems with Fishing, Container and Cruise vessels in the Falklands Islands where Fire mains couplings and seals have been covered in copious amounts of lubricating materials and over time the seals have swelled making a connection almost if not impossible.

We also have a floating dock system here in the islands with it own firefighting mains and after making some enquiries I have been advised that the engineers change the seals that are protected in this manner on an annual basis due to this problem.

 
Wed 07/06/2006 17:07
Hi, I spoke with one of our technical staff as I had come across a similar thing some time ago where we had a facility using Vaseline brand petroleum jelly on an o-ring to lubricate it so that parts could easily be screwed together and it caused swelling and distortion of the o-ring.
 
We think the issue you are dealing with is one of material incompatibility. We doubt that the gaskets were designed with elastomers compatible with petroleum lubricating oils/greases. (Greases contain petroleum lubricating oil). The swelling would be the result of chemical interaction of the lubricating oil with the elastomer.

If you select “lubricating oils (petroleum)” on the left hand side box at the link below, the chemical compatibility of various elastomer will be displayed on the right hand side.

http://www.quickcutgasket.com/chemicalresistance.html

Ratings of 4 are unsuitable for that application. My feeling is that the gasket on the hose is made from elastomer not suitable for petroleum oil service.