Coal Tar Epoxies

[ukciv]

I'm specifying paintwork for a marine environment and a coal tar epoxy has been proposed.

Its a bit of a dirty word in the UK at the minute & from what I understand it will be banned at some point.

Am I right in saying this is only due carcinogen concerns from the fumes during application? i.e. as long as safe working methods are followed it is okay and once it is dry its fine? Its not bio-toxic or anything?

There are alternatives & obviously we do not want to propose anything dangerous but I just want to make sure I take a balanced view.

Thanks

 

[micalbrch]

Coal tar epoxy is not forbidden and as long as the precautions in the Material Safety Data Sheets are obeyed I think you are o.k. There are a lot of common paints for which workes must wear personal safety equipment for handling. I think nobody works for example without a breathing mask when painting with industrial paints.

 

[dik]

There is a strong indication that this is carcinogenic... I would search out other products.

Dik

 

[unclesyd]

Here is some good information on Coal Tar Epoxies and a non Coal Tar Epoxies. The latter is used by a local ship building company in lieu of Coal Tar Epoxy.
Another good line of Epoxies (Bitumastic) are by Carbolin.
I have used all three of these products.

http://www.epoxyproducts.com/coaltar.html

http://www.globalspec.com/datasheet...Coatings/CDB4E2F0-DCD6-41F7-BAD3-85797F185E00

 

[dik]

From...

Occupational Medicine Forum: Cancer and coal tar epoxy resins
Article Abstract:

The evidence of several past studies indicates that pipe coaters exposed on the job to coal tar epoxy resin face a greater risk of cancer. Coal tar epoxy resins are a combination of coal tar and epoxy. Coal tars and coal tar pitches vary in composition; the source of the coal tar and its processing method determine the particular composition of a coal tar and its chemical characteristics. More than 300 compounds have been identified in coal tars. Included are potent cancer-causing substances such as methylcholanthrene, 3,4-benzypyrene and 1,2:5,6-dibenzanthracene. Epoxy resins are a class of thermosetting plastics that are based on ethylene oxide or its derivatives. Fillers, such as asbestos, may be added to the resin or the coal tar, and some epoxy resin systems utilize such solvents as xylene and methyl isobutyl ketone. Workers generally use solvents such as acetone, alcohol, trichloroethylene and methyl ethyl ketone to clean up coal tar epoxy splatters and droplets. A search of the medical and scientific literature does not yield references to animal or human studies of cancer associated with epoxy resins. There is, however, substantial literature on coal tars and the formation of cancer. Documentation of skin cancer associated with coal tars dates back over 200 years. Studies of workers exposed to coal tar have suggested an association with lung, kidney, prostate, bladder, colon, stomach, esophagus, sino-nasal, oral and pancreatic cancers. Some studies have shown an association between coal tars and leukemia and multiple myeloma (a tumor growth, often leading to cancer, in bone marrow). Most of these findings have not been verified; many involve asbestos or benzene exposure that occurred simultaneously with coal tar exposure. The National Institute for Occupational Safety and Health has concluded that coal tar and coal tar pitch are carcinogenic, increasing the risk of lung and skin cancer in workers.

Read more:

http://www.faqs.org/abstracts/Healt...-and-coal-tar-epoxy-resins.html#ixzz1CqN2rUNU

 

[SJones]

Who proposed the coal tar epoxy and what increase in value does it offer over alternatives assuming that they have been qualified to an identical standard?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[ukciv]

I think the main reasons for the continued use of coal tar epoxies in industry is:

1) Price
2) Quick curing times (can be immersed in 1 hour, which is particularly useful in marine environments)
3) Uniformity - it can be shop applied or site applied (for site touch ups at connections/following damage etc)

Its a difficult one - as micalbrch says, if the safety guidelines are followed then it sounds as though it is okay. From what I understand all the risks and concerns are during application, once it is dried its safe, in which case it seems to fall into the category of 'industrial nasty' where strict precautions are required.

The main concern is of course that the realities of site are often a little more laissez faire than we would hope...

I think we will propose a glass flake or high solids epoxy and explain to the Client that coal tar epoxy is an option, but it brings with it site H&S concerns that we would prefer to avoid.

UKCiv

 

[unclesyd]

Not downplaying the warning concerning Coal Tar Epoxies (CTE), but just a reminder that nearly all corrosion resistant coatings carry a warning. For certain applications CTE is hard to beat and can be applied safely using the proper equipment. One area of personnel safety that comes up short is one has to have a chemical fume type respirator along with good hand protection. this all has to coupled with working in ventilated area. You can no apply CTE with a Pine Tree top and Walking Shorts.
I've been around Coal Tar production and use for my life time and the only problem I've seen is burns and Asthma attacks on ASmatics. In CTE's its the catalyst/curing agent that worries me as they are lot of people that will chemical dermatitis from contact, especially the amines.

Addenda:
People who worked in Coal Tar plants never have colds or flu. the was a product that was in th tails of one of the refining columns that was rubbed on cuts to prevent infection. This turn out to have sulfonamide in it. Creosote was a far more dangerous product for people to handle.

 

[SJones]

Just to return to the selection/qualification issue: when you make the proposals to 'the Client', on what basis are the proposals justified? There are a number of performance qualification standards for offshore (marine) coating systems and it may be of some use to quote specific paint systems that have a documented qualification as well as a track record. An example from Jotun is attached.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[ukciv]

All our work is based on the Eurocodes, so all the corrosion protection specifications refer to the relevant clauses of EN ISO 129944-4, EN ISO 8501 and EN ISO 8503-2.

We tend to specify a specific product that would be suitable with 'XXXX or suitable alternative with agreement from the Client's Engineer'. There are a number of propriety systems out there and we don't want to bind tendering contractors to using one particular supplier.

For our marine work all the coating systems have to be prequalified for use in the C5-Marine/Offshore environment other wise they wouldn't even be considered. To be honest I think any Contractor tendering on the basis of a non-qualified system would be discounted...

We received a tender from a Contractor (for another job I'm working on) specifying Coal Tar Epoxy as a suitable alternative to the glass flake system we proposed. In areas requiring abrasion resistance its clear we can argue it should be glass flake but elsewhere - the CTEs are qualified for C5-M, can be immersed within 1 hour and are much cheaper.

I think the best thing we can do is be clear with the Client from the tender document stage - as unclesyd says, maybe CTEs need to just be viewed as industrial coatings that care has to be taken with.

SJones - thanks for that Jotun example, I'll take a look at those products.

 

[rconner]

While I guess I would agree with most of what has already been said, and probably not what you are dealing with, I believe more than forty states in the USA at least now by law or regulation require any substances that come in contact with potable water e.g. coatings in tanks, piping, plants etc. have listings indicating suitability per say NSF Standard 61. I guess it should also be mentioned some authorities or locales have for whatever resons now taken the position that such substances may eventually also involve disposal issues e.g.

http://www.sspc.org/news/coaltar206.html

etc. If you are in an applicale jurisdiction, the manufacturer's MSDS sheet might also prove a valuable reference.

 

[SJones]

Do you also require that any paint system, or the 'suitable alternative', is to be supported by the ageing tests of 12944-6 AND by experience? And, do you also require 'access to documentation confirming the suitability or durability of a paint system'(i.e. the test reports referenced in the Jotun example list)? Really, for marine coatings, you would be much better off packaging ISO 12944 with ISO 20340 wherein 'qualification' is much better defined.

The above reply regarding CTE gives one the impression that CTE is deemed 'qualified' simply because it is shown in Table A.5 of ISO 12944-5.

It is not a means of binding the contractor, it is a means of putting all proposed paint systems on as near a level playing field as possible. Take a scenario when comparing the glass flake with the CTE, neglecting abrasion resistance, what dry film thicknesses are you going to compare? You may find that, for the CTE to match the corrosion protection performance of the glass flake, the DFT has to be doubled or tripled. The cost differential may then not be so attractive if it has to go on in one or more extra coats given that labour is the biggest cost driver.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04