19.2 CODE FORMULA FOR WALL THICKNESS

Codes B31.1 and B31.3 have a different approach to calculation of pipe wall thickness as shown below.

**B31.1 Power Piping Code**

104.1.2 MINIMUM WALL THICKNESS

(Refs: 104.1.2 (A)

Straight Pipe Under Internal Pressure – Seamless, Longitudinal Welded or Spiral Welded and Operating Below the Creep Range.

*(A) Minimum Wall Thickness.*

The minimum thickness of pipe wall required for design pressures and for temperatures `not exceeding those for the various materials listed in the Allowable Stress Tables, including allowances for mechanical strength, shall not be less than that determined by eq.* (3)* or *(4)*, as follows:

Where

*t*_{m}= minimum wall thickness - in. (mm.)

*P* = internal design pressure - psig. (kPa.)

*D*_{o}= outside diameter of pipe as given in tables of standards and specifications - in. (mm.)

*d* = inside diameter of pipe. - in. (mm.). For pressure design calculation, the inside diameter of the pipe is the maximum value allowable under the purchase specification.

*SE* = maximum allowable stress for material and joint efficiency at the design temperature – psi. (kPa.)

*A*= additional thickness to provide for threading, grooving, corrosion, erosion, mechanical strength, etc. – in. (mm.)

*y* = coefficient given in Table 104.1.2(A)

**19.4 FRICTION LOSS CALCULATIONS FOR WATER**

PIPE SIZING (Calculating Pipe Diameter)

The criteria in determining the bore of a pipe is the ‘amount of fluid’ required to flow through it in a specified period of ‘time’. i.e. volumetric flow or mass flow

The units are as follows:

Water or Liquids LPM (litres per minute) or GPM (gallons per minute)

Steam kg /hr (kilogram per hour) or lb/hr (pounds per hour)

Gases m^{3}/hr (cubic meters per hour) or ft ^{3}/hr (cubic feet/hr)

Velocity m/s (meters per second) or ft/sec (feet per second)

#### Above is an excerpt from the chapters of the book: Detail Engineering and Layout of Piping Systems 5th Edition.

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