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What are the requirements for safe distance during Pneumatic Testing of pipeline or pressure vessels?

- mechcolor
- Senior Member
**Posts:**446**Joined:**17 May 2010, 18:05**Area of interest:**Manufacturing Engineering

I have found a reference for safe distance and stored energy calculations for pneumatic testing. It is from ASME PCC-2.

STORED ENERGY CALCULATIONS FOR PNEUMATIC TEST

The stored energy of the equipment or piping system should be calculated and converted to equivalent kilograms (pounds) of TNT (Trinitrotoluene) using the following equations:

E = [1/(k − 1)] x Pat x V [ 1 − (Pa/Pat)^{(k − 1)/k}] (eq. II-1)

where

E = stored energy, J (ft-lb)

k = ratio of specific heat for the test fluid

Pa = absolute atmospheric pressure, 101 kPa (14.7 psia)

Pat = absolute test pressure, Pa (psia)

V = total volume under test pressure, m3 (ft3)

When using air or nitrogen as the test medium

(k = 1.4), this equation becomes

E = 2.5 x Pat x V [1 − (Pa/Pat)^0.286] (eq. II-2)

and

TNT = E / 4266920 (kg) (eq. II-3)

where

E = stored energy, J

Pa = absolute atmospheric pressure, 101 000 Pa

Pat = absolute test pressure, Pa

V = total volume under test pressure, m3

For U.S. Customary units using air or nitrogen as the

test medium (k = 1.4), this equation becomes

E = 360 x Pat x V [1 − (Pa/Pat)^0.286] (eq. II-4)

and

TNT = E / 1488617 (lb) (eq. II-5)

where

E = stored energy, ft-lb

Pa = absolute atmospheric pressure, 14.7 psia

Pat = absolute test pressure, psia

V = total volume under test pressure, ft3

SAFE DISTANCE CALCULATIONS FOR PNEUMATIC TEST

The minimum distance between all personnel and the equipment being tested shall be the greater of

(a) the following:

(1) R = 30 m for E ≤ 135 500 000 J

(2) R = 60 m for 135 500 000 J < E ≤ 271 000 000 J

(3) R = 100 ft for E < 100,000,000 ft-lb

(4) R = 200 ft for 100,000,000 < E ≤ 200,000,000 ft-lb

(b) the following equation:

R = Rscaled (TNT)^(1/3) (eq. III-1)

where

E = stored energy as calculated by eq. (II-1) or (II-2)

R = actual distance from equipment

RSCALED = scaled consequence factor; value for eq. (III-1) shall be 20 m/kg1/3 (50 ft/lb1⁄3) or greater

TNT = energy measured in TNT, kg (lb), determined from eq. (II-3) or (II-5)

Table III-1

RSCALED (m/kg^1/3), RSCALED (ft/lb^1/3) Biological Effect Structural Failure

20 50 . . . Glass windows

12 30 Eardrum rupture Concrete block panels

6 15 Lung damage Brick walls

2 5 Fatal . . .

(Table could not be written in the best format but still will help)

For systems where E > 271 000 000 J (200,000,000 ft-lb), the required distance shall be calculated by eq. (III-1).

If the minimum calculated distance cannot be obtained, an alternative value for RSCALED may be chosen based on Table III-1 for use in eq. (III-1).

For example, to prevent lung damage, the distance a person is from the equipment should result in an RSCALED value of more than 6 m/kg1/3 (15 ft/lb1/3). Note the structural damage that can occur, which shall be considered.

This is as per ASME PCC-2 Article 5.1, Mandatory Appendix II and III.

STORED ENERGY CALCULATIONS FOR PNEUMATIC TEST

The stored energy of the equipment or piping system should be calculated and converted to equivalent kilograms (pounds) of TNT (Trinitrotoluene) using the following equations:

E = [1/(k − 1)] x Pat x V [ 1 − (Pa/Pat)^{(k − 1)/k}] (eq. II-1)

where

E = stored energy, J (ft-lb)

k = ratio of specific heat for the test fluid

Pa = absolute atmospheric pressure, 101 kPa (14.7 psia)

Pat = absolute test pressure, Pa (psia)

V = total volume under test pressure, m3 (ft3)

When using air or nitrogen as the test medium

(k = 1.4), this equation becomes

E = 2.5 x Pat x V [1 − (Pa/Pat)^0.286] (eq. II-2)

and

TNT = E / 4266920 (kg) (eq. II-3)

where

E = stored energy, J

Pa = absolute atmospheric pressure, 101 000 Pa

Pat = absolute test pressure, Pa

V = total volume under test pressure, m3

For U.S. Customary units using air or nitrogen as the

test medium (k = 1.4), this equation becomes

E = 360 x Pat x V [1 − (Pa/Pat)^0.286] (eq. II-4)

and

TNT = E / 1488617 (lb) (eq. II-5)

where

E = stored energy, ft-lb

Pa = absolute atmospheric pressure, 14.7 psia

Pat = absolute test pressure, psia

V = total volume under test pressure, ft3

SAFE DISTANCE CALCULATIONS FOR PNEUMATIC TEST

The minimum distance between all personnel and the equipment being tested shall be the greater of

(a) the following:

(1) R = 30 m for E ≤ 135 500 000 J

(2) R = 60 m for 135 500 000 J < E ≤ 271 000 000 J

(3) R = 100 ft for E < 100,000,000 ft-lb

(4) R = 200 ft for 100,000,000 < E ≤ 200,000,000 ft-lb

(b) the following equation:

R = Rscaled (TNT)^(1/3) (eq. III-1)

where

E = stored energy as calculated by eq. (II-1) or (II-2)

R = actual distance from equipment

RSCALED = scaled consequence factor; value for eq. (III-1) shall be 20 m/kg1/3 (50 ft/lb1⁄3) or greater

TNT = energy measured in TNT, kg (lb), determined from eq. (II-3) or (II-5)

Table III-1

RSCALED (m/kg^1/3), RSCALED (ft/lb^1/3) Biological Effect Structural Failure

20 50 . . . Glass windows

12 30 Eardrum rupture Concrete block panels

6 15 Lung damage Brick walls

2 5 Fatal . . .

(Table could not be written in the best format but still will help)

For systems where E > 271 000 000 J (200,000,000 ft-lb), the required distance shall be calculated by eq. (III-1).

If the minimum calculated distance cannot be obtained, an alternative value for RSCALED may be chosen based on Table III-1 for use in eq. (III-1).

For example, to prevent lung damage, the distance a person is from the equipment should result in an RSCALED value of more than 6 m/kg1/3 (15 ft/lb1/3). Note the structural damage that can occur, which shall be considered.

This is as per ASME PCC-2 Article 5.1, Mandatory Appendix II and III.

- ashfaqanwer
- Site Moderator
**Posts:**857**Joined:**16 Mar 2010, 03:36

Thanks for writing down the complete code for me.

Hope I get the right result out of it. Will look into ASME PCC-2 also.

Hope I get the right result out of it. Will look into ASME PCC-2 also.

- mechcolor
- Senior Member
**Posts:**446**Joined:**17 May 2010, 18:05**Area of interest:**Manufacturing Engineering

It's a long working with formulas but thanks for sharing.

- arcpro
- Senior Member
**Posts:**661**Joined:**16 Apr 2010, 18:46**Area of interest:**Manufacturing Engineering

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