NACE-SP0472-2008.pdf
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1、 Standard Practice Methods and Controls to Prevent In-Service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments This NACE International standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions.
2、Its acceptance does not in any respect preclude anyone, whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE International standard is to be cons
3、trued as granting any right, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by Letters Patent, or as indemnifying or protecting anyone against liability for infringement of Letters Patent. This standard represents minimum requir
4、ements and should in no way be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE International
5、assumes no responsibility for the interpretation or use of this standard by other parties and accepts responsibility for only those official NACE International interpretations issued by NACE International in accordance with its governing procedures and policies which preclude the issuance of interpr
6、etations by individual volunteers. Users of this NACE International standard are responsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE International standard may n
7、ot necessarily address all potential health and safety problems or environmental hazards associated with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE International standard are also responsible for establishing appropriate health
8、, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if necessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE International standards are subject to periodi
9、c review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE International requires that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication and subsequently from the date o
10、f each reaffirmation or revision. The user is cautioned to obtain the latest edition. Purchasers of NACE International standards may receive current information on all standards and other NACE International publications by contacting the NACE International First Service Department, 1440 South Creek
11、Dr., Houston, Texas 77084-4906 (telephone +1 281-228-6200). Revised 2008-11-07 Revised 2005-12-02 Reaffirmed 2000-09-13 Revised October 1995 Revised March 1987 Reaffirmed 1974 Approved April 1972 NACE International 1440 South Creek Dr. Houston, Texas 77084-4906 +1 281-228-6200 ISBN 1-57590-114-5 200
12、8, NACE International NACE SP0472-2008 (formerly RP0472) Item No. 21006 SP0472-2008 NACE International i _ Foreword This NACE standard defines standard practices for producing weldments in P-No. 1 steels resistant to environmental cracking in corrosive petroleum refining environments. It is intended
13、 to be used by refiners, equipment manufacturers, engineering contractors, and construction contractors. Most petroleum refining equipment are constructed from carbon steel having a minimum specified tensile strength to 480 MPa (70,000 psi), and in almost every case, the equipment is fabricated by w
14、elding. The welds for refinery equipment are made to conform to various codes and standards, including the ASME(1) Boiler and Pressure Vessel Code, Section VIII1 for pressure vessels, ASME/ANSI(2) B31.32 for process piping, or API(3) Standards 6203 and 6504 for tanks. According to these codes and st
15、andards, these carbon steels are classified as P-No. 1, Group 1 or 2, and in this standard, they are referred to as P-No. 1 steels. Petroleum refineries as well as oil- and gas-processing plants have predominantly used P-No. 1 steels for services containing wet hydrogen sulfide (H2S), or sour servic
16、es. They are the basic materials of construction for pressure vessels, heat exchangers, storage tanks, and piping. Decades of successful service have shown them to be generally resistant to a form of hydrogen stress cracking (HSC) called sulfide stress cracking (SSC). HSC occurs in high-strength mat
17、erials or zones of a hard or high-strength microstructure in an otherwise soft material. With commonly used fabrication methods, P-No. 1 steels should be below the strength threshold for this cracking. NACE Standard MR01035 provides guidance for materials in sour oil and gas environments in refinery
18、 services, including limiting the hardness of P-No. 1 steels and reducing the likelihood of SSC. NACE Standard MR0175/ISO(4) 151566 provides additional guidance for materials in sour oil and gas environments in production services. In the late 1960s, a number of SSC failures occurred in hard weld de
19、posits in P-No. 1 steel refinery equipment. To detect hard weld deposits caused by improper welding filler metals or procedures, the petroleum refining industry began requiring hardness testing of production weld deposits under certain conditions and applied a criterion of 200 Brinell hardness (HBW)
20、 maximum. These requirements were given in previous editions of this standard and in API RP 942.7 In the late 1980s, instances of heat-affected zone (HAZ) cracking were reported in P-No. 1 steel equipment that met the 200 HBW weld deposit hardness limit. Some cases were determined to be SSC that was
21、 caused by high hardness in the HAZ. Some were identified as another form of hydrogen damage called stress-oriented hydrogen-induced cracking (SOHIC).8 These cracks propagated primarily in the HAZs of weldments and were found in both high- and low- hardness HAZs. Other HAZ cracking instances in spec
22、ific corrosive refinery process environments were attributed to alkaline stress corrosion cracking (ASCC), which can occur as a result of high residual stress levels. HAZ hardness controls and reduction of residual stresses in weldments were outside the scope of early editions of this standard, whic
23、h covered only weld deposit hardness limits. The 1995 revision of this standard was expanded to cover the entire weldment and the various in-service cracking mechanisms (HSC in the weld deposit, HSC in the weld HAZ, and ASCC) that can occur in corrosive petroleum refining environments. _ (1) ASME In
24、ternational (ASME), Three Park Avenue, New York, NY 10016-5990. (2) American National Standards Institute (ANSI), 25 West 43rd St., 4th Floor, New York, NY 10036. (3) American Petroleum Institute (API), 1220 L St. NW, Washington, DC 20005-4070. (4) International Organization for Standardization (ISO
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