THE PRACTICAL REFERENCE GUIDE for WELDING INSPECTION
~ ~ 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 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` STDmAWS PRGVT-ENGL 1999 0784265 051937b 396 E THE PRACTICAL REFERENCE GUIDE for Visual Inspection of Pressure Vessels and Pressure Piping WELDING INSPECTION MANAGEMENT- Ted V. Weber Principal Consultant Weber & Associates This publication is designed to provide information in regard to the subject matter covered. It is made available with the understanding that the publisher is not engaged in the rendering of professional advice. Reliance upon the information contained in this document should not be undertaken without an independent verification of its application for a particular use. The publisher is not responsible for loss or damage resulting from use of this publication. This document is not a consensus standard. Users should refer to the applicable standards for their particular application. American Welding Society 550 N.W. LeJeune Road, Miami, Florida 33126 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` STD-AWS PRGVT-ENGL 1999 W 0784265 0539377 222 AUTHOR NOTES Visual inspection (VT) is one of the more important inspection methods used to ensure the quality of both new fabrication, as well as equipment and piping after some period of service. It is used in all industries, and should be considered as the basic inspection method prior to the selection of any other inspection method. A phrase that puts VT in the proper perspective follows: “lt has been shown repeatedly that an efective program of visual inspection, conducted by properly trained personnel, will result in the discovery of the vast majority of those defects which would otherwise be discovered later by some more expensive nondestructive test method.” Note the emphasis on proper training; 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 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 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 inspectors. 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 that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: 978-750-8400; online: http: //www.copyright.com O 1999 by the American Welding Society. All rights reserved. Printed in the United States of America. Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` ~~ ~ STD-AWS PRGVT-ENGL 1999 W 0784265 0519378 Lb9 m TABLE OF 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-Technical and Scientific Organizations 19 Annex -1998 ACME Boiler and Pressure Vessel Code Sections 22 Annex C-Discontinuities 23 Annex &Selected References 28 iii Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` STD-AWS PRGVT-ENGL 2999 = 0784265 0529379 OT5 E Introduction In one version of a perfect world of manufacturing, there are no inspectors. None are needed because each and every person in the workforce has been so thoroughly trained, possesses and applies all the necessary personal attributes, and is paid a reason- able salary such that all manufacturing mistakes are completely eliminated. Think of that perfect sce- nario: a manufacturing world without mistakes. Some of today's quality approaches reach for that ideal goal and have developed precepts that con- siderably reduce online inspection requirements. The concept of "continuous improvement" is an important part of that quest for perfection, and is found in many quality-concept documents. One approach to quality is found in the documents, modified by American organizations, commonly referred to as IS0 Standards. These often become the basis for "IS0 Certification," which many man- ufacturing sites obtain and market as part of their quality program. In the U.S., these IC0 quality pro- gram standards and guides are published under the combined authority of ANSI (American National Standards Institute), IS0 (International Organiza- tion for Standards), and the ASQ (American Society for Quality), as "Q" documents. Two of these are Q9004-1, Quality Management and Quality System Elements-Guidelines, and Q9001, Quality Systems- Model for Quality Assurance in Design, Development, Production, installation, and Servicing (see Figure 1). A thorough understanding of these two quality documents is very helpful in organizing a Quality Assurance program for fabrication companies. Ad- ditional ASQ documents covering fabrication qual- ity are Q9002, Quality Systems-Model for Quality Assurance in Production, installation, and Servicing, and Q9003, Quality Systems-Model for Quality As- surance in Final inspection andTest. Their cost is min- imal and can be obtained from the American Society for Quality, 611 East Wisconsin Avenue, Milwaukee, WI 53202. However, as much as these new quality programs have improved quality in many areas, in our less- than-ideal, real world, there still remains a need for skilled inspectors. Most have seen various versions of the old saying, "People do whaf you inspect, not what you expect." While that statement appears to be quite cynical, many critical manufacturing ef- forts still follow that credo with great success. In- spection will continue to be a necessary skill for AMERICAN NATIONAL STANDARD AMERICAN SOUM FMI QUAUTY 611 EAST W6co" AMNUE MLWMJKEE. WISCONCIN 5u202 Figure 1. ANSVISO/ASQC Q9001-1994. decades to come, especially in the fabricating in- dustries, and visual inspection will certainly con- tinue on the front line of that inspection effort. In the broad field of Quality Assurance, the control of welding operations and fabrication of process equipment encompasses many technical disciplines including engineering design, materials selection, welding processes, welding procedures, non- destructive inspection, and corrosion mechanisms. Visual inspection plays an important role in all of these and it requires proper training of personnel to provide the necessary function of quality control at each stage of fabrication as well as continued in- spections during the life of the component. Inspector certification programs, such as the AWS CWI and SCWI certifications, have been developed to ensure a basic minimum qualification of the visual inspection personnel (see Figure 2). Other organizations such as the American Petroleum Institute (API), the National Association of Corro- sion Engineers (NACE), and the American Society for Nondestructive Testing (ASNT), have developed AWS Practical Reference Guide 1 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` Figure 2. AWS QC1-96-Standard for AWS Certification of Welding Inspectors. certification programs for general and/or specific industries. Additionally, several industries and pri- vate companies have produced industry-specific or in-house training programs to train the inspectors on their particular needs. Nuclear power industries have such programs, as do the petroleum, petro- chemical, and aerospace industries. Visual inspection is learned through experience; 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 training, 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 properly 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 as part of an inspector’s 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, ductility 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 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). Excerpts 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 requirement 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 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 inspection results must be documented such that they can be referred to months or years later with absolute un- derstanding and clarity. With today’s computer technology, there is little or no excuse not to have complete, clear, legible, and retrievable documenta- tion of inspection results readily available as needed. Today’s 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 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` STD-AWS PRGVT-ENGL 1999 E 07842b5 0519381 753 The Everyday Pocket 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 inspection results. As one inspector noted, ”in today‘s world, if it’s not written down, it hasn’t 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 noted 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 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 operation. 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 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 design 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 group 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 that 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 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` STDmAWS PRGVT-ENGL 1997 0784265 0537382 b7T m welding, or the design makes 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 designed 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 typical 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 construc- 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 inspection 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 usually 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 welding 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 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, 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 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- 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. Coding 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 identification. 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 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 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` ~ STD-AWS PRGVT-ENGL 1999 m 07842b5 0539383 52b Figure 5. ASME Section II, Part A, covering ferrous material specifications. Section II, Part B 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 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 qualify 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, 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.) 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 Pressure 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 never 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 Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` STDOAWS PRGVT-ENGL 1779 111 ANSVAWS ü2.1!1998 An Amorim Naîiml Siandard Specification for Welding Procedure and Performance Figure 7. ANSVAWS 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 activity; many codes require the witnessing and documentation of both the welder performance tests and the mechan- ical testing of the resulting welded test specimens by an inspector. Most codes and other standards cover both the procedure qualification and the welder performance testing. 0784265 0519384 4b2 m Figure 8. ASME Section IX also covers qualification of procedures and personnel for welding. The inspector should be familiar with the period of validity for the welder to remain qualified; this pe- riod is usually noted in the applicable code. Most welder qualifications are valid for a six-month pe- riod, meaning that the qualification is valid as long as the welder performs the same welding process to which he or she qualified. If a welder does not per- form any documented welding with the qualified welding process in the speciried time period, the welder is no longer considered qualified. Some companies adhere strictly to the code qualification requirements; other retest their welders once a year regardless of the code requirements or continuing use of the process. There are several software pro- grams available that aid the tracking of welder qualifications. Central certification of welders is another option that allows a company to maintain records on qualification. Independent third party certifications of welders can provide value by in-, troducing rigorous standardized procedures for 1 6 AWS Practical Reference Guide Copyright American Welding Society Provided by IHS under license with AWS Not for Resale No reproduction or networking permitted without license from IHS ``,``-`-`,,`,,`,`,,` [...]... Welds AWS B1.11 -Guide for the Visual Inspection of Welds AWS A3.û-Standard Welding Terms and Definitions AWC A2.4-Standard Symbols for Welding, Brazing, and Nondestructive Examination AWS B2.1-Specification for Welding Procedure and Performance Qualification AWS -The Practical Reference Guidefor Corrosion of Welds-Causes and Cures NDE Handbook-Non-destructive examination methods for condition monitoring,... equipment inspection, and repair experience Often the equipment must be entered to complete a thorough visual inspection and this requires safe entry procedures and appropriate standby personnel to ensure the safety of all personnel entering the vessels or piping Knowledge of the manufacturing process, the process chemistry, and the equipment being inspected generally lead to completion of the appropriate inspections... can aid in this tracking effort One of the early considerations for fabrication inspection is the necessary type and degree of inspection Often, the fabrication code will specify the inspection requirements but these may not be sufficient for the application While code inspection requirements must be met for compliance, additional inspection may be required However, the inspection philosophy must keep... welding PW-Projection welding FW-Flash welding UW-Upset welding OAW-Oxyacetylene welding OHW-Oxyhydrogen welding PGW -Pressure gas welding X X X X X 1:l X X X CW-Cold welding DFW-Diffusion welding EXW-Explosion welding FOW-Forge welding FRW-Friction welding USW-Ultrasonic welding EBW-Electron beam welding ESW-Electroslag welding IW-Induction welding LBW-Laser beam welding PEW-Percussion welding TW-Thermit... expect, these plants are often built into open structures exposed to the elements and this is an important consideration regarding the inspection requirements The plant will often consist of several miles of process piping of various diameters and alloys, connecting pressure vessel to pressure vessel, and often placed into pipe bridges above ground level Pressure vessels are often placed throughout the. .. for in-service inspections of petrochemical and refinery piping and equipment are: It is also helpful to note the separate definitions given for Inspection and Examination Often we mistakenly use these words interchangeably B31.3 defines them as follows: API 510, Pressure Vessel Inspection Code: Mainfe- Inspection applies to functions performed for the owner by the owner’s inspector or the inspector’s... productivity and cost of filler metal, are the primary drivers Inspection Methods The next item to discuss for organizing the inspection effort is the selection of the required inspection, or inspections, from the various methods available Just as welding processes have advantages and limitations, inspection methods also have these same attributes Some are limited to finding surface discontinuities only; others... PRGVT-ENGL 1999 the fitup inspection to be the most important, others select the root pass as being the most critical inspection point, while still others feel inspecting only the final weld is adequate Sometimes, a combination of these is used for weld inspection: the joint fitup is inspected as well as the root and final pass All of these approaches have been used successfully for field inspection In... Not for Resale ``,``-`-`,,`,,`,`,,` - Undercut is defined as “A groove melted into the base metal adjacent to the weld toe or weld face and left unfilled by weld metal.” Examples are shown in the following figures Annex D-Selected References AWS -The Everyday Pocket Handbookfor Visual Inspection and Weld Discontinuities AWS B1.lO -Guide for the Nondestructive Inspection of Welds AWS B1.11 -Guide for the. .. examination of a percentage of a specified kind of item in a designated lot Type of inspection required Decontamination required for internal inspection Plus others aspects As one moves down the list, the amount of inspection given is decreasing ACME B31.3 specifies one of the above inspection categories depending on the fluid service category selected previously by the engineer The three codes often used for . American Welding Society @ The Practical Reference Guide for Visual Inspection of Pressure Vessels and Pressure Piping Copyright American Welding. 0784265 051937b 396 E THE PRACTICAL REFERENCE GUIDE for Visual Inspection of Pressure Vessels and Pressure Piping WELDING INSPECTION MANAGEMENT-