Writing an Insulation Specification

Gary Bases

July 1, 2005

Understanding or preparing an insulation specification for a high-temperature insulation system is not a simple procedure. It is, in fact, a very complicated process involving multiple variables and the making of many engineering choices. The biggest fallacy is that one specification can work for all situations.

A well-written specification must convey to the installing contractor or personnel, clearly and without exception, the intent of the specification. It must provide the information necessary for the installation to proceed, but does not have to state what is not required. It must list only the things required for the proper installation and supply of the insulation system as defined by the scope. Lastly, a well-written specification will serve to establish proven standard methods of construction.

Regardless of how thorough the specification is written, however, it will not always be practical to cover every conceivable detail that may arise. As is the case in all phases of construction, good common sense and judgment must be exercised in conjunction with any specification. Alternative designs will always be available and can be submitted as options.

An insulation specification should be broken down into four major sections: scope; general conditions; material specifications; and application specifications. The following is considered the minimum requirements per section for a well-written specification.

Section I—Scope

This section should set the boundaries of the work within the specification. It can be relatively short and can be done by a written description, key arrangement drawing or quantitative take-off. Some examples to use for the descriptive scope are:

  • These specifications cover the insulation material and application for the surfaces outlined on the following pages and in accordance with the reference drawings.
  • These specifications cover the insulation material and application for the re-insulation of the entire secondary super heater legs and headers inside the penthouse area.
  • These specifications cover the insulation material and application for the insulation of the economizer casing and associated connecting piping.

Providing a quantitative take-off in the specification is the best way to define work scope. A take-off detailing area by area along with the specific materials and attachments required will eliminate any questions such as: “What materials are required to be used in a specific area?” and “What exactly are the scope limitations?”

Some of the advantages for including a quantitative take-off as the primary means of defining scope are that the defined scope eliminates any misunderstandings that could have an impact on or delay the project during the installation. The defined scope allows the bidding process and the evaluation of the bids to go quicker and easier because the contractors are bidding to the same work scope. It assures that the bid package is complete because the quantitative take-off would point out if there were a drawing or a detail or a question that needed to be clarified prior to the specification going out to the contractors.

The defined scope would act as an actual contract document of what is, or should have been, installed for future reference if problems occur later on. It could be used as historical data for future projects. The defined scope could then be used at the job site to monitor the work being installed quickly and easily, even by those non-experts in the field of insulation.

All of the above are very good reasons to include a quantitative take-off as a scope-defining document. However, the most important reason is that you can estimate material and labor costs before the contractors submit the actual bids. This way you will know exactly what should be a “fair and reasonable” bid. Having your own internal numbers will help in the bid evaluation process. By providing a quantitative take-off with the specifications to the contractors, you have a better chance of getting the project done under budget with far fewer questions and problems during the installation.

Section II—General Conditions

This section should clearly specify what the job conditions are relating to storage, warehousing and responsibilities. It should also tie the specifications to the actual contract agreement that may exist between the customer and the installing contractor. Some examples are:

  • These specifications are to provide for the economic application of the insulation material.
  • Questions concerning application methods as specified in this contract are to be resolved with the company prior to the signing of this contract.
  • The contractor, upon signing this contract, covenants and agrees to the requirements of this contract.
  • All materials required for the proper support and fastening of the insulation system shall be installed by the insulating contractor and be of such quality to be suitable for the purpose intended.
  • Where application drawings differ from actual contract drawings, written specifications, key arrangement drawings and section drawings, the insulation contractor will follow the latter.

Section III—Material Specification

This section must clearly specify what materials can be used. A material can be specified by what it is made of and the manner in which the material was manufactured (e.g., a cellular glass product). A material can be specified by the manufacturer and trade name or number (e.g., XYZ Board Insulation). Lastly, it can be specified by its generic classification and its properties (e.g., mineral wool board ASTM C-612, Type IVB, nominal 8-pound density).

Section IV—Application Specification

This section must state or clearly show by a written specification and/or by application drawings the minimum requirements and accepted standards for applying the insulation. This information will be used as a guide to apply the insulation to the scope of work shown on the actual contract design drawings.

An example of a well-written specification defining application is:

Install 1½-inch-thick mineral wool blanket insulation wired to the secondary super heater tube sections and headers. Where the tube or section spacing is greater than 9 inches, an inner support shall be utilized. Refer to material specifications for approved insulation materials, lacing wire and insulation support. All blanket edges must be sewn together.

Conclusion

It is estimated that in the next five years, the power-generating industry will spend in excess of $35 million to repair or completely replace the insulation (and lagging) that has already been installed on their steam-generating boilers, selective catalytic reducers and other air pollution equipment due to improper installation and design. Many of these errors could have been avoided if a well-written specification had been provided. Having the right specification for the project is the first step to a good installation. Proper installation begins with a clear and defined specification and, if installed correctly, will always end in energy savings.

  
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Figure 1

Figure 1

Writing an insulation specification for high-temperature applications, such as insulation systems at power plants, can be a difficult job.

Figure 2

Figure 2

Downcomer insulation with the wrong size pipe insulation. Notice the packing and the location of the joints.

Figure 3

Figure 3

Furnace wall insulation.

Figure 4

Figure 4

Furnace wall insulation with gaps between the board insulation.

Figure 5

Figure 5

Furnace wall insulation with insufficient insulation pins.

Figure 6

Figure 6

A drawing of pin spacing application.

Figure 7

Figure 7

Furnace wall insulation with irregular pin spacing and pattern.

Figure 8

Figure 8

A 799 F downcomer with insulation being applied.