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Pipework Insulation

1.1    Scope

Pipework insulation is used to reduce the amount of heat lost from pipework containing hot fluids, and the amount of heat gained by pipework containing cold and chilled fluids, thus reducing the amount of energy wasted on maintaining the temperature of the fluids.

The pipework insulation category includes insulation for both lengths of pipe and pipe fittings e.g. flanged joints, valves tees, bends.

The Energy Technology List (ETL) scheme covers six categories of pipework and pipework fittings insulation:

  1.  Refrigeration pipework and fittings
  2.  Chilled water pipework and fittings
  3.  Process pipework and fittings
  4.  ‘Domestic’ space heating & hot water services and fittings (excluding insulation within individual dwellings)
  5.  Non-domestic hot water services and fittings
  6.  Non-domestic space heating services and fittings

To be eligible for inclusion on the ETL, products shall meet the requirements as set out below.

1.2    Definitions

Pipework insulation covers products that are specifically designed to be applied to the outer circumference of a pipe and/or pipe fittings with the primary objective of reducing thermal flow into or out of the pipe. Pipe fittings cover flanged joints, valves, tees and bends.

1.3    Requirements 

1.3.1    Performance requirements  

To be eligible, installations of pipework insulation and fittings shall:

  1. Have an appropriate Conformity Assessment mark.
  2. For categories 1 and 2:
    a.    comply with clause 28.4 of BS 5970:2012 (applicable to cold pipework fittings)
    b.    comply with the relevant clauses, tables and annexes of BS 5422: 2009 as set out in Table 1.1 below.
  3. For category 3:
    a.    comply with clause 28.4 (applicable to cold pipework fittings) or clause 8.4 of BS 5970:2012 (applicable to hot pipework fittings)
    b.    comply with the relevant clauses, tables and annexes of BS 5422:2009 as set out in Table 1.1 below.

    Table 1.1    Relevant clause, table(s) and annex(es) of BS 5422 (2009) used to determine the minimum required thickness for each category of pipework insulation covered by the ETL

     

    Category

    Relevant Clause

    Relevant Table(s)

    Relevant Annex

    1.

    Refrigeration pipework.

    6

    None

    F

    2.

    Chilled water pipework.

    7

    10 & 11

    A

    3.

    Process pipework.

    10

    21

    A

  4. For categories 4, 5 and 6:
    a.    comply with clause 29.2.10 BS 5970:2012 (applicable to hot pipework fittings)
    b.    comply with the maximum permissible heat loss criteria found within Table 1.2, Table 1.3 & Table 1.4 below, which duly form the basis for determining the minimum required thickness of pipework insulation for each category for an eligible installation.

Table 1.2    Maximum Permissible Heat Losses for Domestic Space Heating & Hot Water

Domestic Space Heating & Hot Water
Maximum permitted heat loss (W/m), where temperature = 60oC

Temperature 60oC

Outside pipe diameter (mm)

Permitted Heat loss (W/m)

8

<= 5.82

10

<= 6.20

12

<= 6.52

15

<= 7.03

22

<= 8.02

28

<= 8.87

35

<= 9.63

42

<= 10.58

54

<= 11.83

Table reproduced with kind permission from the ‘ECA Enhanced’ tables of NES Y-50 (2011).

Table 1.3    Maximum Permissible Heat Losses for Non-Domestic Hot Water Supply

Non-Domestic Hot Water Supply

Maximum permitted heat loss (W/m), where temperature = 60oC

Temperature 60oC

Outside pipe diameter (mm)

Permitted Heat loss (W/m)

17.2

<= 6.04

21.3

<= 6.45

26.9

<= 7.00

33.7

<= 7.71

42.4

<= 8.46

48.3

<= 9.01

60.3

<= 9.94

76.1

<= 11.25

88.9

<= 12.17

114.3

<= 14.29

139.7

<= 16.09

168.3

<= 18.24

219.1

<= 22.06

273 and above

<= 25.95

Table reproduced with kind permission from the ‘ECA Enhanced’ tables of NES Y-50 (2011).

Table 1.4    Maximum Permissible Heat Losses for Non-Domestic Heating Supplies

Non-Domestic Heating Installations Maximum permitted heat loss (W/m)

Temperature

Low

Medium

High

 

<=95ºC

96-120ºC

121-150ºC

Outside pipe diameter (mm)

Permitted Heat loss (W/m)

Permitted Heat loss (W/m)

Permitted Heat loss (W/m)

17.2

<= 7.78

<= 10.57

<= 13.27

21.3

<= 8.42

<= 11.25

<= 14.06

26.9

<= 9.05

<= 12.06

<= 15.02

33.7

<= 9.86

<= 13.04

<= 16.07

42.4

<= 10.83

<= 14.12

<= 17.34

48.3

<= 11.42

<= 14.80

<= 18.09

60.3

<= 12.61

<= 16.22

<= 19.62

76.1

<= 14.12

<= 17.88

<= 21.41

88.9

<= 15.28

<= 19.20

<= 22.87

114.3

<= 17.51

<= 21.66

<= 25.53

139.7

<= 19.72

<= 23.99

<= 27.98

168.3

<= 22.34

<= 26.63

<= 30.69

219.1

<= 26.61

<= 31.15

<= 35.25

273 and above

<= 30.91

<= 35.83

<= 40.05

Table reproduced with kind permission from the ‘ECA Enhanced’ tables of NES Y-50 (2011).

Where:

  • Where “<=” means “less than or equal to”
  • If the pipe diameter differs from the parameters used to generate these tables, then linear interpolation methods may be used to calculate the maximum permissible heat flows and, in combination with information on the thermal conductivity of the chosen product at the relevant mean temperature, the minimum required thickness of insulation.
  • If the parameters of the specific installation are outside the scope of these tables (e.g. different ambient air temperature, or linear interpolation is not possible) then the minimum required thickness of insulation shall be calculated using BS EN ISO 12241:2008.
  • BS EN ISO 12241:2008 shall be used to calculate the pipework heat gains for refrigeration pipework insulation needed to comply with clause 6.3.2 of BS 5422:2009.

1.4    Measurement and calculations

1.4.1    Measurement standards

The following standards, where applicable, shall be used for measuring and calculating product performance:

  • BS 5422:2009 Method for specifying thermal insulating materials for pipes, tanks, vessels, ductwork and equipment operating within the temperature range -40°C to +700°C
  • BS EN ISO 12241:2008 Thermal insulation for building equipment and industrial Installations. Calculation rules
  • BS 5970:2012 Thermal insulation of pipework, ductwork, associated equipment and other industrial installations in the temperature range of -100°C to +870°C. Code of practice
  • NES Y-50 (2011)

1.4.2    Performance metrics

Minimum pipework insulation thickness must be specified to meet the heat loss/gain metrics listed and/or referenced in the tables above, according to the product’s thermal conductivity.

1.4.3    Test requirements

Manufacturers shall provide a Declaration of Performance (DoP) to declare the thermal conductivity used to calculate pipework thickness. Standardised assumptions used to calculate the heat loss according to EN ISO 12241:2008 are to be submitted for categories 4, 5 & 6. This shall include ambient air temperature, surface emissivity, operating temperature and orientation.

1.4.4    Rounding 

For the avoidance of doubt, thermal conductivity test data should be presented to 3 decimal places. 

1.5           Verification for ETL Listing

Any of the following testing routes may be used to demonstrate the conformity of products against the requirements:

  • In-house testing – Self-certified
  • In-house testing – Self-tested and verified or cross-checked by an independent body
  • Witnessed testing
  • Independent testing
  • Representative testing for categories 4, 5 and 6 only (see clause 1.5.1)

Further information regarding the five routes can be found in Guidance Note 5 on the ETL product testing framework [1].

1.5.1       Representative Testing

Representative testing may be used for pipework insulation products that fall under the following categories:

  • ‘Domestic’ space heating & hot water services (excluding insulation within individual dwellings)
  • Non-domestic hot water services
  • Non-domestic space heating services

Where applications are being made for two or more pipework insulation products that are made from the same insulating material, with the same thermal conductivity, representative testing may be used. Test data for the pipework insulation material may be used to determine product performance for all pipework insulation products in the representative range.

Under this method, product performance shall be demonstrated by calculating the permitted heat loss (W/m) for the relevant outside pipe diameter. Manufacturers shall submit supporting information regarding the calculation method, in order to determine its suitability and effectiveness. Thermal conductivity (W/m.K) i.e. the lambda value, shall be determined for the pipework insulation material through product testing.

It should be noted that:

  • If any product submitted under these representative testing rules is later found not to meet the performance criteria when independently tested, then all products based on the same representative model will be removed from the ETL.

1.6    Conformity testing

Products listed on the ETL may be subject to the scheme’s conformity testing programme in order to ensure listed models continue to meet the ETL requirements.

1.7    Review 

1.7.1    Indicative review date 

This specification is scheduled to be reviewed during the 2023/24 review cycle.
 

[1] https://www.gov.uk/government/publications/energy-technology-list-etl-product-testing-framework