SPREADSHEETS SERIES No. 0003S


Wall Thickness Calculation of Straight Pipes Under Internal Pressure

Calculation as per par. 403.2 Criteria for Pipe Wall Thickness and Allowances by ASME B31.4 for D/t > 20


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

Diameter Nominal, DN =	mm	Longitudinal Weld Joints =

External Diameter, D =	mm	Material =

Internal design pressure (gauge), Pi =	barg	Design Temperature =			85	ᵒC
		Design temp. between −29°C and 120°C
Location =				Well joint factor, E =
See table 403.3.1-1		See table 403.2.1-1
Design factor, F =		Spec. min. yield strength, Sy =				MPa
See table 403.3.1-1
Allow. for corrosion, A =	mm



CALCULATIONS
				Check for Applicability
Applicable allowable stress value, S =	MPa			D/t =
				D/t ≥ 20

Thickness for design pressure, t =	mm	t =	PiD
		t =	20S

Nominal thickness as per 403.2.1, tn =	mm	tn = t + A
Minimum thickness required
Nom. pipe wall thickness T ≥ tn =	mm
From ASME B36.10M (Thickness most commonly used)
SCH =	(Minimum acceptable when applicable)


Wall Thickness Calculation of Straight Pipes Under Internal Pressure

Calculation as per par. 403.2 Criteria for Pipe Wall Thickness and Allowances by ASME B31.4 for D/t > 20


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

Nominal Pipe Size, NPS =	in	Longitudinal Weld Joints =

External Diameter, D =	in	Material =

Internal design pressure (gauge), Pi =	psig	Design Temperature =			ᵒF
		Design temp. between −20°F and 250°F
Location =				Well joint factor, E =
See table 403.3.1-1		See table 403.2.1-1
Design factor, F =		Spec. min. yield strength, Sy =			psi
See table 403.3.1-1
Allow. for corrosion, A =	in



CALCULATIONS
				Check for Applicability
Applicable allowable stress value, S =	psi			D/t =
				D/t ≥ 20

Thickness for design pressure, t =	in	t =	PiD
		t =	2S

Nominal thickness as per 403.2.1, tn =	in	tn = t + A
Minimum thickness required
Nom. pipe wall thickness T ≥ tn =	in
From ASME B36.10M (Thickness most commonly used)
SCH =	(Minimum acceptable when applicable)


	Discussion and References
	Information about Wall thickness calculation of straight pipes under internal pressure:
	ASME B31.4 Transportation Systems for Liquids and Slurries, para. 403.2.1

	Tables and Standards
-	ASME B31.4 Specified Minimum Strength - US Units
-	ASME B31.4 Specified Minimum Strength - Metric
-	Table 403.2.1-1 Weld Joint Factors Applicable to Common Pipe Specifications
-	Table 403.3.1-1 Allowable Values for Pipeline System Stresses
-	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 under internal pressure (403.2.1):

	For D/t > 20, the wall thickness should be calculated by the equations:

	t =	PiD	(U.S. Customary Units)
	t =	2S	(U.S. Customary Units)

	t =	PiD	(SI Units)
	t =	20S	(SI Units)

	tn = t + A

	The parameters in the wall thickness calculation of straight pipes under internal pressure
	equations above are:
	t = thickness for design pressure, in. (mm).
	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).
	tn = nominal thickness, in. (mm).
	S = Applicable allowable stress value, psi (MPa), as determined by the following equation:

	S = F x E x Sy		(See table 403.3.1-1 of ASME B31.4)

	Where:
	F = design factor based on nominal wall thickness, see table 403.3.1-1.
	E = weld joint factor as specified in table 403.2.1-1
	Sy = specified minimum yield strength of the pipe, psi (MPa).