SPREADSHEETS SERIES No. 0006S


Wall Thickness Calculation of Straight Pipes on Offshore Liquid Pipeline Systems

Calculation as per Chapter IX by ASME B31.4 for D/t ≥ 30


(Enter values in yellow cells for calculations and in blue cells as information)
DATA INPUT

Diameter Nominal, DN =	mm	Material =

External Diameter, D =	mm	Design Temperature =			ᵒC
		Design temp. between −29°C and 120°C
Location =		Internal design pressure (gauge), Pi =			barg
See table A402.3.5-1
Hoop stress design factor, F1 =		Water Depth, H =			m
See table A402.3.5-1		Water Density, ɣ =			Kg/m³
		External pressure (gauge), Pe =			barg
Allow. for corrosion, A =	mm
optional		Spec. min. yield strength, Sy =			MPa



CALCULATIONS
				Check for Applicability
Applicable allowable stress value, S =	MPa			D/t =
				D/t ≥ 30

Nominal thickness as per chapter IX, t =	mm	t =	(Pi-Pe)D
Minimum thickness required		t =	20S

Nominal thickness + Corr. Allow., tn =	mm	tn = t + A

Nom. pipe wall thickness, T ≥ tn =	mm
From ASME B36.10M (Thickness most commonly used)
SCH =	(Minimum acceptable when applicable)

- Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.


Wall Thickness Calculation of Straight Pipes on Offshore Liquid Pipeline Systems

Calculation as per Chapter IX by ASME B31.4 for D/t ≥ 30


(Enter values in yellow cells for calculations and in blue cells as information)
DATA INPUT

Nominal Pipe Size, NPS =	in.	Material =

External Diameter, D =	in.	Design Temperature =			ᵒF
		Design temp. between −20°F and 250°F
Location =		Internal design pressure (gauge), Pi =			psig
See table A402.3.5-1
Hoop stress design factor, F1 =		Water Depth, H =			ft
See table A402.3.5-1		Water Density, ɣ =			lb/ft³
		External pressure (gauge), Pe =			psig
Allow. for corrosion, A =	in.
optional		Spec. min. yield strength, Sy =			psi



CALCULATIONS
				Check for Applicability
Applicable allowable stress value, S =	psi			D/t =
				D/t ≥ 30

Nominal thickness as per chapter IX, t =	in.	t =	(Pi-Pe)D
Minimum thickness required		t =	2S

Nominal thickness + Corr. Allow., tn =	in.	tn = t + A

Nom. pipe wall thickness, T ≥ tn =	in.
From ASME B36.10M (Thickness most commonly used)
SCH =	(Minimum acceptable when applicable)

- Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.


	Discussion and References
	Information about Wall thickness calculation of straight pipes on Offshore Liquid Pipeline Systems:
	ASME B31.4 Transportation Systems for Liquids and Slurries, chapter IX.

	Tables and Standards
-	ASME B31.4 Specified Minimum Strength - US Units
-	ASME B31.4 Specified Minimum Strength - Metric
-	Table A402.3.5-1 Design Factors for Offshore Pipeline Systems
-	ASME B36.10M-Welded and Seamless Wrought Steel Pipe
-	ASME B36.19M-Stainless Steel Pipe
-	ASTM A377 Ductile Iron Pressure Pipe
-	ASTM A691 Electric-Fusion-Welded Steel Pipe for High-Pressure Service at High Temperatures

	Equations for Wall thickness calculation of straight pipes on Offshore Liquid Pipeline (chapter IX):

	For D/t ≥ 30, the wall thickness should be calculated by the equations:

	t =	(Pi-Pe)D	(U.S. Customary Units)
	t =	2S	(U.S. Customary Units)

	t =	(Pi-Pe)D	(SI Units)
	t =	20S	(SI Units)

	tn = t + A		Corrosion allowance is not included in the chapter IX
			It is optional to the designer its inclusion in the calculation.

	The parameters in the wall thickness calculation of straight pipes on Offshore Liquid Pipeline
	equations above are:
	Pe = external pressure, psig (barg).
	Pi = internal design pressure, psig (barg).
	D = external diameter, in. (mm).
	A = sum of corrosion allowance, slots, threads and safety in special areas, in. (mm).
	t = nominal thickness, in. (mm) as per chapter IX.
	S = Applicable allowable stress value, psi (MPa), as determined by the following equation:

	S = Fi(Sy)

	Where:
	F1 = hoop stress design factor from Table A402.3.5-1.
	Sy = specified minimum yield strength, psi (MPa)

	* Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.