Safe Distance for Pneumatic Test

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Safe Distance for Pneumatic Test

Postby mechcolor » 14 Aug 2010, 12:18

What are the requirements for safe distance during Pneumatic Testing of pipeline or pressure vessels?
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Re: Safe Distance for Pneumatic Test

Postby ashfaqanwer » 19 Aug 2010, 15:43

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.
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Re: Safe Distance for Pneumatic Test

Postby mechcolor » 20 Aug 2010, 05:14

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.
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Re: Safe Distance for Pneumatic Test

Postby arcpro » 04 Sep 2010, 22:35

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