Calculate minimum safe distances between piping system being pneumatically tested and personnel/plant facilities using ASME PCC-2 Mandatory Appendix 501-II and III equations. For details on the basis of this calculation and example manual calculation refer to the article on Pneumatic Testing - Safe Distances.
The calculation is based on air or nitrogen being used as test medium with specific heat ratio of k = 1.4.
Output
The total pneumatic test pressure volume is
The absolute test pressure in Pascals is
The absolute atmospherice pressure in Pascals is 101000 Pa
The value of Stored Energy in Joules is
The equivalent Stored Energy in kilograms of TNT is
Stored Energy in Joules is calculated using formula
Stored Energy (E) = 2.5 * Pt * V \(\left[1-\left(\frac{P_a}{P_t}\right)^.286\right]\) ..... as per equation II-2 from ASME PCC-2 Appendix 501-II.
where
Pa = absolute atmospheric pressure = 101,000 Pa
Pt = absolute test pressure
V = total volume under test pressure
Stored Energy in terms of kilograms of TNT is calculated using
TNT = \(\frac{Stored Energy}{4,266,920}\) (kg) ..... as per equation II-3 from ASME PCC-2 Appendix 501-II
If E <= 135,500,000 J, the safe distance to be maintained is greater of 30m or R calculated as per equation III-1 below.
If E > 135,500,000 J and less than equal to 271,000,000 J, the safe distance to be maintained is greater of 60m or R calculated as per equation III-1 below.
If E > 271,000,000 J
Safe Distance (R) = Rs(2TNT)1/3..... as per equation III-1 from ASME PCC-2 Appendix 501-III.
where Rs = scaled consequence factor whose minimum value shall be 20m/kg(1/3).