ASME code

ASME Code, Article II, Subsection A, Section V, Boiler and Pressure Vessel Code, 1983. 

Fuel Gas Piping (B31.2) is no longer an ANSI/ASME code. See American Gas Association (AGA) National Fuel Gas Code, Z223.1. 

Many other codes, standards, specifications, and recommended practices have been developed by various organizations (26). Some apply to specialized piping systems others, particularly those covering materials and dimensions, are referenced in the ANSI/ASME Code for Pressure Piping. 

Storage tanks should be designed in accordance with the ASME code for unfited pressure vessels. AH-welded constmction is recommended. Ethylene oxide storage tanks should be electrically grounded, isolated from potential fire hazards, and equipped with pressure rehef devices. New equipment should be cleaned of iron oxide and immediately purged with inert gas. 

Special operating conditions and miscellaneous items Table 10-12 is based on the API and ASME codes. 

Where the word code is rrsed in this srrbsection of the Handbook withorrt other identification, it refers to the B31.3 section of ANSI B31. The code has been extensively qrroted in this srrbsection of the Handbook with the permission of the prrblisher. The code is prrbhshed by and copies are available from the American Society of Mechanical Engineers (ASME), 345 East 47th Street, New York, New York 10017. References to the ASME code are to the ASME Boiler and Pressrrre Vessel Code, also prrblished by the American Society of Mechanical Engineers. 

Nominal pressure stresses shall not exceed the yield strength at temperature (see Table 10-49 and data in ASME Code, Sec. TII, Division 2). 

The qualification of brazing procedures, brazers, or brazing operations is required in accordance with the requirements of Part QB, Sec. IX, ASME Code, except that for Category D fluid seiwice at design temperatures not over 93°C (200°F). Such qualification is at the owners option. The clearance between surfaces to be joined by brazing or soldering shall be no larger than is necessary to allow complete capillary distribution of the filler metal. 

Personnel performing examinations other than visual shall be qualified in accordance with applicable portions of SNT TC-IA, Recommended Practice for Nondestructive Testing Personnel Qualification and Ceitification. Procedures shall be qualified as required in Par. T-150, Art. 1, Sec. Vof the ASME Code. Limitations on imperfections shall be in accordance with the engineering design but shall at least meet the requirements of the code (see Tables 10-58 and 10-59) for the specific type of examination. Repairs shall be made as applicable. 

Visual examinafion shall be performed in accordance with Art. 9, Sec. V of the ASME Code. 

Radiography of components other than castings and of welds shall be in accordance with Art. 2, Sec. V of the ASME Code. Limitations on imperfections in components other than castings and welds shall be as stated in Table 10-58 for the degree of radiography involved. 

Piping required to have a sensitive leak test shall be tested by the gas- and bubble-formation testing method specified in Art. 10, Sec. V of the ASME Code or by another method demonstrated to have equal or greater sensitivity. The sensitivity of the test shall be at least (100 Pa mL)/s [(10 atm mL)/s] under test conditions. If a hydrostatic pressure test is used, it shall be carried out after the sensitive leak test. 

Because of the demands of highway service, the DOT specifications have a number of requirements in addition to the ASME Code. These include design for impact forces and rollover protection for fittings. 

Code Administration The American Society of Mechanical Engineers has written the ASME Boiler and Pressure Vessel Code, which contains rirles for the design, fabrication, and inspection of boilers and pressure vessels. The ASME Code is an American National Standard. Most states in the United States and all Canadian provinces have passed legislation which makes the ASME Code or certain parts of it their legal requirement. Orrly a few jurisdictions have adopted the code for all vessels. The others apply it to certain types of vessels or to boilers. States employ inspectors (usually under a chief boiler inspector) to enforce code provisions. The authorities also depend a great deal on insurance company inspectors to see that boilers and pressure vessels are maintained in a safe condition. 

The ASME Code is written by a large committee and many subcommittees, composed of engineers appointed by the ASME. The Code Committee meets regularly to review the code and consider requests for its revision, inter pretation, or extension. Interpretation and extension are accomplished through code cases. The decisions are piibhshed in Mechanical Engineering. Code cases are also mailed to those who subscribe to the service. A typical code case might be the approval of the use of a metal which is not presently on the list of approved code materials. Inquiries relative to code cases should be addressed to the secretary of the ASME Boiler and Pressure Vessel Committee, American Society of Mechanical Engineers, New York. 

Inspection Authority The National Board of Boiler and Pressure Vessel Inspectors is composed of the chief inspectors of states and municipalities in the United States and Canadian provinces which have made any pari of the Boiler and Pressure Vessel Code a legal requirement. This board promotes uniform enforcement of boiler and pressure-vessel rules. One of the board s imporiant activities is providing examinations for, and commissioning of, inspectors. Inspeciors so qualified and employed by an insurance company state, municipality, or Canadian province may inspect a pressure vessel and permit it to be stamped ASME—NB (National Board). An inspector employed by a vessel user may authorize the use of only the ASME stamp. The ASME Code Committee authorizes fabricators to use the various ASME stamps. The stamps, however, may be apphed to a vessel only with the approval of the inspector. 

ASME Code Section VIII, Division 1 Most pressure vessels iisedin the process indiistiy in the United States are designed and constructed in accordance with Sec. TH, Division I (see Fig. 10-187). This division is divided into three subsections followed by appendixes. 

FIG. 10-187 ASME Code Sec. VIII, Division 1 applicable paragraphs for design and construction details. (Courtesy of Missouri Boiler and Tank Co.). 

ASME Code Sec. Ill Nuclear Power Plant Components This section of the code includes vessels, storage tanks, and concrete containment vessels as well as other nonvesseJ items. 

The ASME Codes recommend that hydrostatic tests be run at a temperature that is usually above the nil-ductility temperature of the material. This is, in effect, a pressure-temperature treatment of the vessel. When tested in the relatively ductile condition above the nil-ductihty temperature, the material will yield at the tips of cracks and flaws and at points of high residual weld stress. This procedure will... 

Pressure vessels carried aboard United States-registered ships must conform to rules of the U.S. Coast Guard. Subchapter F of Title 46, Code of Federal Regulat ions, covers marine engineering. Of this. Parts 50 through 61 and 98 include pressure vessels. Many of the rules are similar to those in the ASME Code, but there are differences. 

Vessels for high-temperature serviee may be beyond the temperature hmits of the stress tables in the ASME Codes. Sec tion TII, Division 1, makes provision for construction of pressure vessels up to 650°C (1200°F) for carbon and low-alloy steel and up to 815°C (1500°F) for stainless steels (300 series). If a vessel is required for temperatures above these values and above 103 kPa (15 Ibf/in"), it would be necessaiy, in a code state, to get permission from the state authorities to build it as a special project. Above 815°C (1500°F), even the 300 series stainless steels are weak, and creep rates increase rapidly. If the metal which resists the pressure operates at these temperatures, the vessel pressure and size will be limited. The vessel must also be expendable because its life will be short. Long exposure to high temperature may cause the metal to deteriorate and become brittle. Sometimes, however, economics favor this type of operation. 

Lined vessels are used for many applications. Any type of lining can be used in an ASME Code vessel, provided it is compatible with the metal of the vessel and the contents. Glass, rubber, plastics, rare metals, and ceramics are a few types. The hning may be installed separately, or if a metal is used, it may be in the rorm of clad plate. The cladding on plate can sometimes be considered as a stress-carrying part of the vessel. 

The British Code (British Standards) and the West German Code (A. D. Merkblatter) in addition to the ASME Code are most commonly permitted, although Netherlands, Sweden, and France also have codes. The major difference between the codes lies in fac tors of safety and in whether or not ultimate strength is considered. ASME Code, Sec. TH, Division 1, vessels are generally heavier than vessels... 

Construction Codes Rules for Construction of Pressure Vessels, Division 1, which is part of Section T11 of the ASME Boiler and Pressure Vessel Code (American Society of Mechanical Engineers), sei ves as a construction code by providing minimum standards. New editions of the code are usually issued every 3 years. Interim revisions are made semiannually in the form of addenda. Compliance with ASME Code requirements is mandatoiy in much of the United States and Canada. Originally these rules were not prepared for heat exchangers. However, the welded joint between tube sheet and shell of the fixed-tube-sheet heat exchanger is now included. A nonmandatoi y... 

Shell and Tube Heat Exchangers for General Piefineiy Seivices, API Standard 660, 4th ed., 1982, is published by the American Petroleum Institute to supplement both the TEMA Standards and the ASME Code. Many companies in the chemical and petroleum processing fields have their own standards to supplement these various requirements. The Jnterrelation.ships between Codes, Standards, and Customer Specifications for Proce.ss Heat Tran.sfer Equipment is a symposium volume which was edited by F. L. Rubin and pubhshed by ASME in December 1979. (See discussion of pressure-vessel codes in Sec. 6.)... 

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