coating specification

Specifying Coatings

Part 1: Specifications Simplified

Independent of the type of coating project, a properly prepared specification is a key component to its success. A coatings specification describes the project and the objective of the coating system. It also describes the surface preparation requirements, materials required to specifying coatingscomplete the work, the intended appearance of the completed work, and lists the inspection check points to help assure that the work is done according to the specification. The coating specification for a project should be read and understood by all parties involved in the project (before the project begins), including the facility owner’s representatives, the coating manufacturer, the inspector and the contractor personnel assigned to the project.

Who Typically Prepares the Specification?

Some contracts may simply require that the work be performed in accordance with the coating manufacturer’s instructions.  However, for most projects, the facility owner prepares a detailed project specification, or contracts an outside engineering firm to prepare one. The manufacturer(s) of the coatings that will be used on the project should be involved in the specification development process to ensure that the correct coatings are being specified and that the cleaning and painting requirements are suitable for their products.

Is a Coating Specification a Legal Document?

A coating specification is a legally binding document. It is a contract between the owner and the contractor. When the project goes well, the detailed requirements of a coatings specification rarely come into play. However, in the event the project does not go well and legal actions are pursued, the specification becomes a critical document in the suit. It is important that the specification be written so that the project manager, foreman and workers can perform the work without confusion. The best written specifications are well-organized and use simple language that is easy to understand.

A coating specification should be practical, so that the owner can effectively communicate the desired outcome. The specification should not be unreasonably restrictive, but should anticipate problem areas that the contractor may encounter and must overcome to successfully complete the contract. A well-prepared coating specification benefits both the facility owner and the contractor’s crew, and should be written in a non-adversarial tone to foster teamwork between the owner, contractor and material supplier to achieve the end goal: long term corrosion protection.

Prescriptive Verses Performance-based Specifications

Many coating specifications are prescriptive in that they provide the contractor with the means and methods to accomplish the work, rather than simply indicating the desired end-result. This can be a mistake, in that the contractor’s hands are tied regarding the use of innovative methods in which to accomplish the work. In a performance-based specification, while some directions are required (e.g., the contractor shall dry abrasive blast clean the steel using a recyclable abrasive to achieve SSPC-SP10, Near-white Blast and a 2-3 mil angular surface profile), the means and methods of achieving this level of surface preparation (abrasive size, nozzle size, air pressure, distance from nozzle to surface, blast nozzle angle, etc.) are left to the contractor. Another risk in developing a prescriptive specification is that if the prescribed means and methods do not achieve the end-result, claims against the owner and project cost overruns can occur.

It should be evident that the preparation of a well-written, thorough coating specification is not a simple task, and should be done with great care to avoid contract disputes and coating failure.

Part 2: Specifying Coating Systems

There are several ways that coating systems can be specified for use on a project. Some specifications are written around specific product trade names, and some are written as “trade name or equal.” Others are based on a pre-established “Qualified Products Lists” (QPL), or are based on a set of performance standards. While infrequent, a coating system can also be specified based on a coating formulation or a set of formulations. The principle advantages and limitations of each are listed below.

Specifying Coatings by “Trade Name”

Advantages:

  • High rate of success if use is based on past performance
  • Facility owner has full knowledge of the material based on past use
  • Manufacturer stands behind the product and provides advice/guidance to help ensure proper installation

Limitations:

  • Potentially high material costs (no competition)
  • Products can be changed even though the brand names remain the same
  • Problematic on projects involving public funding (government agencies), since sole sourcing is difficult

Specifying Coatings by “Trade Name or Equal”

Advantages:

  • If “or equal” product is truly equal in performance, competitive pricing can be established

Limitations:

  • “Or equal” needs to be defined. Determining “or equal” should be based on performance testing or historical use of the product/system in the same/similar service environment. Acquiring this data can be time consuming and evaluating “or equal” status can be subjective

Specifying Coatings by “Qualified Products Lists”

Advantages:

  • Establishes “equivalent” performance based on successful field use and/or laboratory testing
  • Competitive pricing established with little risk of acquiring sub-standard product

Limitations:

  • The time period required to establish a QPL
  • Cost of testing to attain QPL status may be passed on to facility owner by the coating manufacturer via higher material costs
  • Random tests of supplied batches may be required to confirm that the material being supplied is the same as the material that was originally qualified

Specifying Coatings by “Performance”

Advantages:

  • Any coating that meets/exceeds performance requirements can be selected for use. This avails the facility owner to potentially more options for corrosion prevention than the other methods.
  • Specified performance standards are typically prepared by industry trade organizations as consensus standards (e.g., SSPC Paint 36), indicating that they have been developed by a mix of owners, vendors, engineers, and contractors across many industries.

Limitations:

  • Testing prescribed by the performance standard may be short term laboratory testing and may not mimic the prevailing service environment
  • Field exposure testing of candidate coating systems to assess performance can be costly and time consuming
  • Unless carefully written, the specification may open the project up to many different generic coating types, which may not be in the best long term interest of the owner

Specifying Coatings by “Formulation” (e.g., MIL-P-24441, Formula 150, 151, 154; aka Mare Island Epoxy)

Advantages:

  • Various coating manufacturers can supply formula-based products, since the formula is published
  • Many formulas have a history of successful use in various service environments

Limitations:

  • Coating manufacturer follows formula and does not conduct performance evaluations to verify performance. Once the product passes to the facility owner, the manufacturer has no responsibility for performance provided it was formulated according to specification
  • Formulation may have been developed based on laboratory testing verses field performance
  • Formulations are antiquated and cannot keep up with new technology or improved formulations – they do not take advantage of the R&D money being spent by coating manufacturers to improve products
  • Raw materials used to formulate coatings may be inferior, but still conform to the minimum requirements of the specification

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