1、 STD*AWS PRGVT-ENGL 1777 E 07842b5 0539375 45T LI American Welding Society The Practical Reference Guide for Visual Inspection of Pressure Vessels and Pressure Piping STDmAWS PRGVT-ENGL 1999 0784265 051937b 396 E THE PRACTICAL REFERENCE GUIDE for Visual Inspection of Pressure Vessels and Pressure Pi
2、ping WELDING INSPECTION MANAGEMENT- Ted V. Weber Principal Consultant Weber without such training, the inspector often only looks at things without actually inspecting them, and critical discontinuities are often overlooked. It is to that end, the training of vi- sual inspectors, that this Guide was
3、 prepared. Proper visual inspection requires inspector training in many disciplines and the training should be a continuous, ongoing process. New technologies useful to visual in- spection are continuing to be developed, and these must be incorporated into the overall inspection efforts to optimize
4、results. It was once stated that, “lnspectors must have been haEfcrazy to have selected inspection as a lifetime career!” While many of us may agree with that statement in part, most would agree that inspection is a very challenging and catisQing career path, and we remain quite proud to be called i
5、nspectors. Ted V. Weber Hendersonville, Tennessee Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use only, or the internal, personal, or educational classroom use only of specific clients, is granted by the American Welding Society (AWS) provided t
6、hat the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: 978-750-8400; online: http: / O 1999 by the American Welding Society. All rights reserved. Printed in the United States of America. STD-AWS PRGVT-ENGL 1999 W 0784265 0519378 Lb9 m TABLE OF
7、CONTENTS Page No . Introduction 1 New Fabrication . 3 Base Metals and Filler Metais 4 Welding Procedure Qualification 5 Personnel Qualification 6 Inspection Planning . 7 Repairs and Re-inspection 9 Production Welding-New Fabrication . 10 Fabrication Codes 12 In-Service Inspection . 14 Annex A-Techni
8、cal and Scientific Organizations . 19 Annex -1998 ACME Boiler and Pressure Vessel Code Sections . 22 Annex C-Discontinuities 23 Annex al- most everyone has the inherent capability to see things, but visual inspection requires a more thor- ough observance of details that requires consider- able train
9、ing, and the learning curve is usually very experience-intensive. One of the first requirements of a visual inspector in the fabricating realm is to be able to read and interpret engineering drawings. Unless the inspector has this first capability, the re- quirements of the fabrication cannot be pro
10、perly determined. Many inspectors learn blueprint read- ing in school, either in a drafting or engineering drawing course; others learn on the job. The method of learning to interpret fabrication draw- ings is not the important issue. Rather, it is the in- terpretation itself that must be included a
11、s part of an inspectors skills. Slang terms and incorrect terminology often lead to confusion and errors. So, a second requirement is to know and understand the proper terminology per- tinent to a given industry. Proper terminology in- cludes the mechanical aspects of stress, strain, strength, ducti
12、lity and many others that aid in de- scribing the mechanical properties of the materials used in manufacture. It also includes the necessary terminology of welding and fabrication processes, including joint and weld geometry and welding processes as well as typical discontinuities. Various base and
13、weld metal discontinuity types have been defined by AWS and are described in AWS 81.10, AWS B1.ll, AWS A3.0, and in the convenient AWS publication The Everyday Pocket Handbook for Visual Inspection and Weld Discontinuities-Causes and Rem- edies (see Figure 3 and Annex D-Selected Refer- ences). Excer
14、pts from some of these are found in Annex C-Discontinuities. Knowledge of corro- sion terms is also required when completing in-ser- vice inspections of pressure equipment. Corrosion terms can also be found in several of the references noted in Annex D-Selected References. An important third require
15、ment for the visual in- spector is a thorough knowledge of the fabrication codes pertaining to the various industries. The pe- troleum industry relies on API specifications, the railroad industry relies on the AAR standards, and building construction relies on the AWS structural codes. Almost every
16、industry has specific codes that pertain to their particular needs and the inspec- tor must have access to, and be familiar with, the applicable codes. A fourth requirement is precise documentation of inspection results. Verbal statements regarding in- spections usually have little value; the inspec
17、tion results must be documented such that they can be referred to months or years later with absolute un- derstanding and clarity. With todays computer technology, there is little or no excuse not to have complete, clear, legible, and retrievable documenta- tion of inspection results readily availab
18、le as needed. Todays technology also includes the excel- lent digital cameras that permit photographs of the equipment or condition to be easily inserted into the records. Video cameras are another method of 2 AWC Practical Reference Guide STD-AWS PRGVT-ENGL 1999 E 07842b5 0519381 753 The Everyday P
19、ocket Handbook for Visual Inspection and Weid Discontinuities- Causes and Repairs Compiled as a useful tool for on-the-job welding personnel by the AWS Product Development Committee Figure 3. The Everyday Pocket Handbook for Visual Inspection and Weld Discontinuities-Causes and Repairs. recording in
20、spection results. As one inspector noted, ”in todays world, if its not written down, it hasnt happened!” It is certainly recognized that the actual require- ments for thorough visual inspection may vary from one industry to another, but all visual inspec- tion contains the four basic requirements no
21、ted above that must be met to inspect an item to the de- sired and required level. Inspection not only applies to the original fabrication of the components, but extends to the in-service inspections as weli. Fitness for purpose inspections must often continue for the life of the component, and this
22、 usually requires some form of periodic inspection, performed to written guidelines, to ensure the continued safe op- eration of the item. Most are somewhat familiar with the stringent rules for continued inspection for aircraft; they receive periodic inspections after a set number of hours of opera
23、tion. Many pressure ves- sel codes have similar requirements but usually have longer time periods between inspections. It is not the purpose of this Guide to repeat in great detail all the visual inspection procedures found in these other documents. Rather, practical ap- proaches to the broad topic
24、of visual inspection will be covered, both for new fabrication and in-service inspections. The emphasis will be on piping and vessels for pressure containment. New Fabrication A good starting point for any new fabrication project is close communication between the manu- facturing personnel and the d
25、esign groups. To use a petrochemical process as an example, the manufac- turing group knows the task it wants to perform whether it is to manufacture polyester sheeting ma- terial, polyethylene pellets for molding machines, or acids to use as ingredients for other manufactur- ing processes. The grou
26、p conveys its desired result to the design group and after several discussions and iterations, the final design of the component is completed. During this design stage, it is very help- ful to have input from the welding and metallurgi- cal engineers as well as the inspectors to assist in a design t
27、hat first of all can be fabricated, and sec- ondly, inspected adequately. All too often, designs are too quickly put together only to find out the materials selected pose tremendous difficulty in AWS Practical Reference Guide 3 STDmAWS PRGVT-ENGL 1997 0784265 0537382 b7T m welding, or the design mak
28、es it impossible to thor- oughly inspect. The design of each separate component for a com- plex process is sometimes done in a rather random fashion. For example, a vessel is needed to mix the raw ingredients and is designed by the pressure vessel group. Then a distillation column is needed and is d
29、esigned by the distillation column design- ers. A heat exchanger is needed and is designed by the heat exchanger designer. When insufficient communication exists between these various groups, it can lead to costly redesign, or material changes, to incorporate exactly what is needed. Figure 4. A typi
30、cal petrochemical complex showing the complexity and variety of pressure vessels and piping arrangements. A far better approach is to have good liaison be- tween the various design sections through a project manager to ensure compatibility of each compo- nent, especially regarding the materials of c
31、onstruc- tion and corrosion issues. The selection of materials incorporates many different aspects including cost, availability, strength, weldability, and corrosion re- sistance. Selection of the correct material may re- quire fabrication and corrosion testing to ensure suitability. Visual inspecti
32、on of these corrosion tests may be an initial inspection requirement for the project, and requires an understanding and knowl- edge of the various corrosion tests by the inspector. Often these are done to ASTM specifications and the inspector must have ready access to them. Pressure containment usua
33、lly requires the use of welding operations in the manufacturing of the piping and vessels needed. In the fabrication of new equipment, the welding operations usually get considerable attention up front. There are several reasons for this, but they often include the general lack of knowledge of weldi
34、ng techniques by many of the engineering staff as well as previous experi- ences with weld failures. A list of the initial require- ments for fabrication inspection will usually include the following: Base Metals and Filler Metals These should be purchased to specifications listing all the necessary
35、 requirements, with a supporting Material Test Report requirement on the purchase order. These necessary requirements usually in- clude the mechanical properties, chemistry, size, shape, manufacturing method, surface finish, heat treatment, and quantity. Base metals are often or- dered to ASTM, ASME
36、, or API specifications; filler metals are usually ordered to AWS specifications. Specific items may require additional data, such as the protective coatings for corrosion resistance of steel products or shipping container requirements for low-hydrogen electrodes, and all the materials should always
37、 be inspected upon receipt to ensure compliance. Often, for critical applications, check analyses on the chemistry or mechanical properties may be made to reflect a higher degree of certainty. For filler metals, this may require the preparation of a weld sample to a specification for chemical or me-
38、 chanical testing, with its preparation witnessed by an inspector. Once the proper materials have been received and confirmed, it is imperative that storage of these ma- terials maintains their proper identification (ID). There are many different systems used for main- taining the ID of materials. C
39、oding by different paint colors can be an acceptable method for mate- rials control, but consideration should be given to the effects of sun and weather on the color. Color changes do occur with exposure to sun, and this must be recognized. Color changes over time have led to mistakes in alloy ident
40、ification. Weather can also cause deterioration of the materials, and pro- tection may be needed during storage. Piping is often ink marked every three or four feet along its length with its specification, grade, heat number, etc., which helps maintain its identifica- tion. Plate is often stamped or
41、 paint marked with its ID on one corner. Consider what happens if a por- tion of the plate is used. Often, the corner with the 4 AWS Practical Reference Guide STD-AWS PRGVT-ENGL 1999 m 07842b5 0539383 52b Figure 5. ASME Section II, Part A, covering ferrous material specifications. Section II, Part B
42、 of the same code covers nonferrous materials. Figure 6. ASME Section II, Part Cy covering filler metals. The AWS Filler Metal Specifications were adopted for use in Part C. marking is taken for use and this requires the re- marking of the “drop” or remainder. Inspectors should, and often do, play a
43、 role in this remarking. Other items such as forgings, castings, or subassem- blies may require bar coding, stamping, tagging, or segregation to maintain their identity. ways depending on the code requirements in effect for the project. In some codes, test weldments must be made and tested to qualif
44、y a procedure. Other codes may permit the use of “canned” welding pro- cedures or the use of mockups. The inspector must be familiar with the procedure qualifications and ensure they are met completely and satisfactorily. Welding Procedu re Qual if cat ion Once the base materials have been received,
45、 con- firmed, and stored properly, the next item requiring attention for fabrication of pressure containment equipment is the qualification of welding proce- dures. (This step may be the initial step in the entire process if the fabricator has little or no experience with the materials to be used.)
46、A welding process is selected and a preliminary Welding Procedure Specification is usually prepared. However, these procedures can be qualified in several different Two of the more common procedure qualification approaches are those found in the AWS standard B2.1:1998, and the ASME Boiler and Pressu
47、re Vessel Code, Section IX (see Figures 7 and 8). Either may be acceptable but if an ASME Code fabrication is being produced, Section IX is required for proce- dure qualification. Too often, once a welding procedure has been qual- ified, it disappears into the dark corners of some office and is neve
48、r seen again except during formal audits. While a master list of procedures with current copies should be maintained in an office, AWS Practical Reference Guide 5 STDOAWS PRGVT-ENGL 1779 111 ANSVAWS 2.1!1998 An Amorim Naiml Siandard Specification for Welding Procedure and Performance Figure 7. ANSVA
49、WS 82.1 :1998 can be used for welding procedure and personnel qualification. copies of those welding procedures should also be placed in binders or protected with plastic covers and made readily available at the shop floor to the welding and inspection personnel. This simple step often eliminates many procedural mistakes during fabrication. Personnel Qualification Once the necessary welding procedures have been qualified, the next step is to qualify the welders and welding operators to the applicable code. The in- spector has a key role to play in this ac
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