Wall thickness calculations - using B31.3 CodeĪNSI/ASME Standard B31.3 is a very stringent code with a high safety margin. This could be significantly higher than the flowing pressure of the fluid in the pipe. Please note that the allowable internal pressure is the maximum pressure to which the piping system can be subjected. A variety of steel pipe sizes, wall thicknesses, and material grades are available for petroleum piping and pipeline applications. and larger sizes refer to the outside diameter.
refer to the approximate ID measurement of Schedule 40 or “standard” wall, whereas nominal 14 in. The “nominal” commercial pipe sizes from 1/8 through 12 in. Table 1 illustrates a number ANSI pipe schedules, for reference. Steel pipe is available in a variety of commercial sizes ranging from nominal 1/8 up to 60 in. Modern steel pipe manufactured to these exacting standards assures both high quality and safety in design. All of these standards have very rigid design, specification, chemistry, and testing standardization and manufacturing requirements. for Testing and Materials (ASTM), ASME, and ANSI standards are used most often. However, for the vast majority of the “pressure” piping systems encountered, steel pipe is required.įor petroleum applications, pipe materials that meet American Petroleum Inst. Utility systems such as those for water, sanitary or storm water, air, draining or low-pressure oil or gas service applications often use the nonsteel piping material systems. There are some applications where plastic, concrete, or other piping materials are both desirable and acceptable. The engineer should check to see if there are different standards that must be applied in the specific location of the design. For simplicity, we will discuss only the U.S. In other countries, similar standards apply with minor variations. Some companies use the more stringent ANSI/ASME Standard B31.3 for onshore facilities. Most onshore facilities are designed in accordance with ANSI/ASME Standard B31.4 or B31.8, depending on whether it is an oil or gas facility. In the U.S, piping on offshore facilities is mandated by regulation to be done in accordance with ANSI/ASME Standard B31.3. This standard applies to gas transmission, gathering, and distribution pipelines onshore. ANSI/ASME Standard B31.8, Gas Transmission and Distribution Piping Systems.This standard applies to onshore oil pipeline facilities. ANSI/ASME Standard B31.4, Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols.This standard applies to major facilities onshore and offshore worldwide. ANSI/ASME Standard B31.3, Chemical Plant and Petroleum Refinery Piping.This standard applies to steam piping systems. ANSI/ASME Standard B31.1, Power Piping.of Mechanical Engineers (ASME) specify wall-thickness requirements. The following standards from the American Natl. The basic formula for determining pipe wall thickness is the general hoop stress formula for thin-wall cylinders, which is stated as The design engineer must verify whether the particular country in which the project is located has regulations, codes, and standards that apply to facilities and/or pipelines. The design and operation of gathering, transmission, and distribution pipeline systems are usually governed by codes, standards, and regulations. If there are no codes or standards that specifically apply to the oil and gas production facilities, the design engineer may select one of the industry codes or standards as the basis of design. The safety factor or code design application.
There are many factors that affect the pipe-wall-thickness requirement, which include: Once the inner diameter (ID) of the piping segment has been determined, the pipe wall thickness must be calculated. This is discussed below in the section on velocity considerations for pipelines. (In addition, there may be velocity constraints that might dictate a larger pipe diameter. The fluid flow equations and formulas presented thus far enable the engineer to initiate the design of a piping or pipeline system, where the pressure drop available governs the selection of pipe size. 3.9 Control valves and pressure - relief/safety devices.3.6 Minimum wall thickness - pipe and fittings.3 Valve, fitting, and flange pressure ratings.1.7 Wall thickness calculations - comparisons.1.6.7 Comparions of the different classes.1.6 Location Classes for Design and Construction.1.5 Wall thickness calculations - using B31.8 code.1.4 Wall thickness calculations - using B31.4 Code.1.3 Wall thickness calculations - using B31.3 Code.