Pipe wall thickness

For pipelines in service in chemical plants, it is not usually convenient to place a radiation source inside the pipe and position it to irradiate each welded joint. The radioisotope source container maybe placed on the outer surface of the pipe. The radiation beams then pass through two pipe wall thicknesses to expose films placed diametrically opposite the radiation source, also on the outside of the pipe wall. Other methods, such as magnetic particle inspection of welds in steel pipe, or ultrasonic inspection of welds in pipes of all materials, supplement x-rays in many critical appHcations. The ultrasonic tests can often detect the thin, laminar discontinuities parallel to the pipe surface or the incomplete fusion discontinuities along the weld... 

Pipe-Wall Thickness. Once the design pressure and temperature have been established and the pipe material and size selected, the wall thickness is calculated using the appropriate section of the code. In rare cases, a thin pipe must be made thicker to withstand handling. Occasionally the thickness is affected by external loads or vibrations. All codes prescribe essentially the same design formula for metallic hoUow circular cylinders under internal pressure ... 

However, is dependent on the ratio of hole diameter to pipe diameter, pipe wall thickness to hole diameter ratio, and pipe velocity to hole velocity ratio. As long as all these are small, the coefficient 0.62 is generally adequate. 

P = hquid bulk modulus of elasticity E = elastic modulus of pipe waU D = pipe inside diameter b = pipe wall thickness... 

Software packages are commercially available for simulation of hydrauhc transients. These may be used to analyze piping systems to reveal unsatisfactoi y behavior, and they aUow the assessment of design changes such as increases in pipe-wall thickness, changes in valve actuation, and addition of check valves, surge tanks, and pulsation dampeners. 

Internal surfaces were moderately tuberculated (Fig. 3.14). Extremely thick, hard magnetite shells capped large internal cavities (Fig. 3.9). Pipe cross-sectional area was reduced by at least 30% in some places. Tubercles were aligned with flow, indicating that growth occurred during service. No failure occurred, and deepest metal loss was only 0.093 in. (0.033 cm) from the nominal pipe wall thickness of 0.225 in. (0.572 cm). 

Sample Specifications 3.5 in. (8.9 cm) outer diameter, carbon steel pipe, wall thickness -0.225 in. (0.572 cm)... 

On-site inspection of regions near the emergency service water intake structures revealed loss of up to 40% of the nominal pipe-wall thickness. Deposits were dried, ignited, and analyzed. A 1% solution of dried ash had... 

Fig. 10-1 Length of the protected range 2 Z- as a function of pipe wall thickness and proteetion eurrent density from Eq. (10-5) the pipeline (p, = 0.18 X 10 m, 5 = 8 mm DN 600) with insulated soekets is bridged by 0.5-m NY Y eable of 16 mm eopper.

REF No. DUTY NOM BORE iiun/ins PIPE WALL THICKNESS TYPE CLASS MATERIAL BRANCH COMPENTN REMARKS 55 56... 

Maximum allowable working pressure MAWP) Highest pressure to which the system can be subjected during operation. Thus, pressure is established by a relief device set pressure and must be less than or equal to the material strength limitations of equipment. This pressure e.stabli.sh-es piping class for fittings and pipe wall thickness requirements, both of which are discussed in Volume 1. 

The pipe wall thickness is selected to resist the internal pressure, with an allowance for corrosion. Processes pipes can normally be considered as thin cylinders only high-pressure pipes, such as high-pressure steam lines, are likely to be classified as thick cylinders and must be given special consideration (see Chapter 13). 

This relation determines the pipe wall thickness required to withstand a fluid pressure P in a pipe of radius R made of a material with a working stress a. 

The dimensionless pipe wall thickness (times 1000) is known as the Schedule number of the pipe ... 

Using the actual dimensions of commercial steel pipe from Appendix F, plot the pipe wall thickness versus the pipe diameter for both Schedule 40 and Schedule 80 pipe, and fit the plot with a straight line by linear regression analysis. Rearrange your equation for the line in a form consistent with the given equation for the schedule number as a function of wall thickness and diameter ... 

T = pipe wall thickness (measured or minimum per purchase specification) t — pressure design thickness, as calculated in accordance with para. IP-3.2.1 for internal pressure or as determined in accordance with para. IP-3.2.2 for external pressure tm — minimum required thickness, including mechanical, corrosion, and erosion allowances W = weld joint strength reduction factor per para. IP-2.2.10... 

T = nominal pipe wall thickness, in. ok = hoop stress due to design pressure, ksi... 

A dent may be defined as a depression that produces a gross disturbance in the curvature of the pipe wall (as opposed to a scratch or gouge, which reduces the pipe wall thickness). The depth of a dent shall be measured as the gap between the lowest point of the dent and a prolongation of the original contour of the pipe in any direction. 

T Pipe wall thickness (measured or minimum per purchase specification) mm in. 

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