Spectacle blinds: protective coating - best practices

[GinoDL]

Hi All,

When spectacle blinds are installed in a piping lay-out, after some time they start to corrode and finally the contact surface is damaged in that way the spectacle blind cannot be used anymore to assure a positive isolation of the piping part.

At the moment I am busy to create a best practice for protection of spectacle blinds for our company, but it seems that there are several statements/opinions about this issue. One of the possibilities is to use Tectyl to protect the surface, but wath about the several service conditions and the compatibilty with different kinds of media. The idea is to have a solution that is universal applicable with low cost!

Has anybody set-up already some recommendations/best practices about this topic! I would appreciate if your experiences could be shared. Examples of best practices / recommendations are always welcome.

Best regards,

Gino

 

[pennpiper]

For this question and your other one for "Bolts" you have not told us the source of the corrosion.
Is this job site near the ocean and thus subject to high salt spray? What is the source?

Without any other information my suggestion is as follows:
Spec Blinds:
Don't use "Figure 8" blinds, use only the two piece "Paddle" and "Spacer". If the "Spacer" is installed then keep the "Paddle" in the warehouse, greased and labeled.

If you already have "Figure 8" blind then at the first opportunity, cut them apart and do as suggested.

For the bolts, keep a good dose of grease on them and then plan on replacing them the next time you need to remove them.

 

[GinoDL]

Hello Pennpiper,

Thank you for the reply.
Indeed the source of the corrosion can be the result of several conditions, but I have approached this subject as general as possible, since we are talking about a group strategy for different locations with different environmental conditions.

These environmental conditional are not only related to the atmospheric influence, but also by the chemical emissions, which are also different in all locations.

The idea is to set-up an easy to use best practice for all locations, with minimal cost impact.

Regarding the use of 'spectacle blinds',indeed we had this discussion also, and the dissicion has been taken to use 'figure 8 blinds' for sizes up to 6". Above this we go indeed for the "paddle" and "spacers" approach.

What kind of grease are you using for the storage. We were thinking about the use of Tectyl 506.

RFor the bolting we are now investigating the use of 'Dracomet' coatings. Any experience with this or with any other coating system?

BR

Gino

 

[gerhardl]

What kind of service for the pipelines, and what type of material for the blinds?

If 'general best practice' also drinking water? (Then tectyle is out, and you have to use grease non-soluted in normal temp water, allowed edible type).

What about upgrading all blinds to non-corrosive material and earthing to protect against galvanic corrosion?

 

[GinoDL]

Hello gerhardl,

All kinds of services that you kind find in refinery/petrochemical plants are possible. Let's assume that drinking water services is an exception in this case.

The protection system were I am thinking about is to be applied after installation of the spectacle in the piping lay-out and protect the spectacle for several months/years (with periodic inspection of course).

The blind material is mostly specified as A516 gr60.

Upgrading to non-corrosive will be not possible due to the financial impact and the long time that will be necessary to replace.
Earthing due to galvanic corrosion is possible, but most visual corrosion is a result of the atmospheric and weather conditions.

BR

Gino