Annual Conference News and Events Specifications Heat and Frost Denis Formula TIAC Times Members

 

12. DENIS FORMULA – REVISION #4 – METRIC

12.2 STANDARD METHOD OF MEASUREMENT
FOR INSTALLED INDUSTRIAL INSULATION

These standards are to be used for the express purpose of measuring the quantities of insulation required for a mechanical system. They can be used for tendering, evaluation of bids, and for finalizing accounts.

SCOPE

1. Insulation of mechanical systems including, but not limited to, vessels, equipment, exchangers, pumps, tanks, ducts or flues and pipe work.

2. All measurements shall be taken on the external surface of the insulation system.

3. There shall be no deductions for surfaces not insulated within the specified insulation area. Exceptions to this rule may be negotiated where termination of insulation does not require a finish or weatherproofing and/or where the uninsulated portion is more than 5% of the total.

4. Irregular shapes, fittings on piping systems, valves, etc., shall be counted separately. The conversion tables of the formula are designed to include for general requirements. Conversion factors for unusual items, e.g. seismological anchor or hangers, shall be negotiated by the parties prior to commencing the work.

5. All obstructions and penetrations of the insulation system shall be measured separately.

6. All effected areas and pipe lengths shall be multiplied by the complete applicable unit prices.

DEFINITIONS

Types of insulation: hot, anti-condensation, cryogenic, acoustic, fireproofing.

General description of items to be insulated:

(a) Vessels

Towers, columns, drums, containers, receivers, exchangers, storage tanks, etc.

(b) Equipment

Equipment which has an irregular outer surface, e.g. transitions, stiffeners, heads, roof ends, turbines, pumps, compressors, air or gas handling fans, etc.

(c) Flat Surfaces

Boiler walls, precipitators, hoppers, ducts & flues, storage bins, etc.

(d) Piping

Straight pipes, bends, elbows, accessories, fittings, valves, flanges, strainers, termination points, bevels, etc.

(e) Instruments

Measuring and controlling devices for process requirements.

(f) Height allowances

Standards, see page DF-6.

PRINCIPALS OF MEASURING EQUIPMENT

Shell – Cylindrical

The outside diameter of the vessel plus two times the insulation thickness multiplied by 3.14 and by the length, tangent line to tangent line, as illustrated in diagram. Transition sections (changes in diameter) shall be measured using the larger diameter, times the length. There shall be no deductions for manholes and any other interruption or projection, whether insulated or not.

Irregular Surfaces

Any irregular shape shall be measured on the outside of the insulation surface, using the largest diameter. The surface area for irregular surfaces to be multiplied by a correction factor of 1.75 to obtain the equivalent area of flat surface. For small pumps, turbines, etc. the minimum equivalent area of measurement shall be 1 sq. meter.

Heads, Roofs, Ends

Flat: The surface area with diameter outside of the vessel insulation.

Spherical: The surface area of the hemisphere with diameter outside of the vessel insulation.

Dished: The surface area of a flat circle with a diameter outside of the vessel insulation, multiplied by a correction factor of 1.37.

Cones: The geometrical surface area of the cone, measured outside the insulation thickness.

ADDITIONAL MEASUREMENTS

On "Unit Price" contracts, all insulated nozzles and man-ways connecting to a vessel will be measured as pipe run to the vessel wall plus flange. In addition, all nozzles, man-ways, brackets, platform supports, obstructions, and penetrations, shall have their perimeter measured as irregular surface. All penetrations shall be a minimum 0.1 sq. meter per each.

On "Lump Sum" contracts, where like obstructions, penetrations, nozzles, brackets, supports, stiffener rings, etc. have not been shown in detail on bid drawings, they shall be measured, as above, as extra work to the contract.

PRINCIPALS OF MEASURING

PIPING

Pipe shall be measured from center line to center line through all fittings, in accordance with Diagram 'A', Page 10. All fittings will be counted and classified for multiplication by the appropriate factor listed in the "Fitting Factor Tables" Pages 5 to 8. Fittings connecting two or more different sizes of pipe shall be counted as the largest size involved.

Bent Pipe:

Shall be measured on the outside radius of the bend(s),

Traced Piping:

Insulation sized to accommodate tracer(s) shall be measured at the actual size of insulation used.

Tracer loops shall be measured separately.



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