addition of a new layer of rubber lining

[davidet68]

One of our sub supplier have performed a rubber lining inside two our vessels. The thickness in some points was 3.3 mm instead of the required 4 mm (tollerance +/- 10%). Our client's inspector rejected the vessels and we have proposed to add an additional layer of 2 mm of rubber lining. Our client reject our proposal stating that this solution (add a new layer on an already vulcanized one) is not accetable. Is it true? If my sub supplier pay attention to avoid to have a too high hardness on the first layer, is there any other problem? Thank you! Davide

 

[sokos]

I think that your client is right. The best way is to have ny one layer with the required thickness. Otherwise, you should make special treatment such that the two layers work as if they are 1 layer.

 

[cub3bead]

I wouldn't accept it! Tell your sub to rip it out and start over.

 

[davidet68]

I cleary understand that the better solution is to remove the existing layer and add a new one, but this will cause a big delay in my delivery! Checking the BS 6374 is clear that the requirement of a defined thickness (in my case 4mm) +/- 10% is referred to the rubber sheet before vulcanization. My client is rejecting a mesurament done after the application and vulcanization of the rubber lining, but I have not found any point which refers to the thickness of the final rubber lining: have you any further iformation on this points?
Morover: you say that you would ask for a completely new layer, but what is the technical reason to not accept a second layer added to the first one?
Thank you,
Davide

 

[cub3bead]

How do you insure that the second layer will adhere to the first? I realize that holidays are repaired by chemically vulcanizing a patch over the rubber lining but repairs are typically << 1% of the total surface area. You are talking about a 100% patch. I would be concerned with the second layer disbonding and forcing the owner to take the equipment out of service.

Did you spark test the lining?

Have you considered offering an extended warranty?

Why didn't your inspector catch this?

The question you have to answer is what will delight my client? And the answer is a lining that meets his specifications otherwise he wouldn't have spec'ed a 4 mm lining nor would he have sent an inspector to the shop to inspect the lining.

 

[davidet68]

We have performed the sparking test, the hardness test, etc and we have also proposed to extend the guarantee of two more years pointing out that the actual rubber lining is of a good quality and with a thickness of 3.3 mm minimum which is clearly not critically thin.

It is obvious that my client want a good lining, but he have indicated in his spec 4 mm without any other detail, therefore, according to BS 7463 he would have check the thickness of the rubber sheet and not of the final lining. Now, it is clear that he prefer to have 4 mm even after vulcanization and he is asking for this, but, on the other side I can not do everything he ask me if there is no real requirement otherwise I will never finish my job and I will loose a lot of money.
This is the reason why I'm asking for further information on this problem. Bye, Davide