Extending Bridge Service Life Through Field Welded Repairs and Retrofits (2016)

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19 installation, and quality control and quality assurance requirements for field welding projects. The following design requirements were investigated: – Plan and specification preparation, and – Base material properties. The following installation requirements were reviewed: – In-house versus contracted welders, – Certified welders, and – Welding and inspection procedures. The following installation requirements were inves- tigated: – Welding inspector requirements, and – NDT requirements. • Field Weld Performance and Case Examples—This section of the survey focused on the performance of field welded repairs and retrofits and whether the respondents had experienced field welding that could be shared as either a successful or not successful field welded project case example. The first question in this section asked whether agencies have had any major problems asso- ciated with repairs and/or retrofits specifically because they were field welded. If yes, respondents were asked to describe such issues. Respondents were then asked whether they had an experience with field welding on a project, either successful or not, which could be used as a case example. Additional information was then col- lected on the specific field welded project and whether the respondent was satisfied or not with the field welding on this project. Survey results are presented in the remainder of this chapter. Representatives from six state DOTs were interviewed to develop case examples of specific field welded projects, which are presented in chapter four. EXTENT OF FIELD WELDING Field Welding Policy Of the 43 state DOTs that responded to the survey, 32 (74%) reported that their agency allows planned field welded repairs and retrofits to be performed. Of the 11 agencies (26%) that do not allow planned field welded repairs/retrofits, two (5%) have previously performed field welding. The remaining nine agencies (21%) have never performed and do not currently allow field welding. Figure 4 shows which agencies allow field OVERVIEW To better understand the current (2015) field welding practices used by state transportation agencies, a survey of practice was conducted through NCHRP in cooperation with AASHTO. Each of the voting members of the AASHTO Subcommittee on Bridges and Structures (SCOBS) was by e-mail for the survey. SCOBS voting members were encouraged to for- ward the survey to the individual in their agency who would be most familiar with that agency’s field welding practices. E-mail reminders were sent to encourage participation. Forty- three state DOTs completed the survey, an 86% response rate. This chapter summarizes the current practices as derived from the survey. The information is presented in various for- mats, including both tables and graphs, as appropriate. A copy of the survey questionnaire is included in Appendix B and the agency responses are presented in Appendix C. SURVEY CONTENT Survey questions were organized into the following three categories: • Policy on Field Welding—The first question in this section asked participants whether their agency allows planned field welding repairs or retrofits. If not, partici- pants were asked why they chose not to and if they had ever performed planned field welding. If their agency currently does not allow planned field welding and has not ever performed planned field welding, participants were finished with the survey. If their agency either allows planned field welding or has performed planned field welding, participants completed the remainder of the survey. These participants were asked whether their agency has any standard plans, specifications, proce- dures, or details for certain field welded repairs. If yes, they were asked to provide such information by upload- ing them electronically or provided a link to any hosted files. Participants were then asked if there was a govern- ing specification or welding code and, if so, what welding code was applied. Finally, participants were requested to describe the types of field welded repair and retrofits that their agency has performed. • Field Welding Project Details—This section of the survey gathered information about the typical design, chapter three STATE OF THE PRACTICE

20 welding currently, allowed field welding previously but do not currently allow it, and which agencies have never allowed field welding. States as far north as Alaska, North Dakota, Minnesota, and Maine allow field welding; there does not appear to be a correlation with lowest anticipated temperatures and general geographic location and the propensity for field welding. Figure 5 displays the reasons that 11 state DOTs do not allow field welding that included: • Lack of experienced inspectors, • Lack of qualified agency supervisors or administrators, • Quality of work, • Unfamiliarity with appropriate welded details, • Past issues, FIGURE 4 Allowance of field welding. FIGURE 5 Reasons for not allowing field welding.

21 • Expense or time consuming, • Unfamiliarity with process and/or welding, and • Other (please specify). The most common reason for why agencies do not allow field welding was concerns regarding the quality of work, as indicated by eight of the 11 agencies. The other most often cited responses were a lack of experienced inspectors and a lack of qualified agency supervisors or administrators. Three agencies selected “other” with the following explanations: • Past performance, • Welding to a member that is under stress or load, and • Preferred approach is to provide a structural bolted connection, and the use of field welding is only used as a last resort where there is insufficient room to develop a bolted connection. The rest of the survey included questions only provided to the 34 agencies that either currently allow field welding or have previously performed planned field welding. Reasons for Field Welding Most field welding projects can be grouped into the following three categories. Fatigue Improvement This typically includes retrofit of out-of-plane and distortion- induced cracking by welding the connection stiffener to the tension flange. Welding of the transverse stiffeners and con- nection plates to the tension flange was avoided prior to the early to mid-1980s owing to concerns over fatigue cracking. As a result, a positive rigid connection between the girder flange and web-mounted stiffeners and connection plates was generally not provided. The lack of a positive connection often resulted in cracking from out-of-plane distortions in a plane parallel to the primary loading stress. Capacity Strengthening The typically involves a retrofit to increase capacity as the result of a poor load rating such as adding cover plates to a rolled beam bridge. These members are not necessarily dam- aged and may have been designed to support a lighter load than under current specifications. Corrosion and Impact Damage Strengthening This includes repair or retrofit of damaged members. These members may have corrosion damage that has resulted in sig- nificant section loss and either requires additional strengthen- ing or complete replacement of the member. Impact damage typically results in distorted and damaged members, including cracking or tearing of the bridge member. To better understand the most common reasons for field welding, the agencies were asked to select each of the com- mon types of field welding projects they have performed or provide any others that do not fall into these categories. The results are shown in Figure 6. The most common type of field welded project performed was corrosion and impact damage strengthening, with 30 of the 34 possible respondents (88%) reporting that they have performed this type of field weld- ing project. The second most common choice was capacity strengthening. “Other” was selected by one agency, and it elaborated on this choice by describing the use of field welding to reconnect secondary members and to add plates in com- pression zones. This would likely fall into both the capacity strengthening and corrosion and impact damage strength- ening categories. FIGURE 6 Types of field welding projects.

22 Field Welding Staff Some agencies may use field welding often enough that they have in-house welders. For other agencies who undertake field welding less often, this may not be economical when compared with hiring an outside contractor to perform these duties. The agencies were asked whether they do field welding with an in-house welding staff, outside contractors, or both depending on the project. Figure 7 shows the answers to this question. It was found that most agencies (20 of 34) contract out their field welding projects. Some agencies use both outside con- tractors and internal staff, whereas only three use in-house. CURRENT MANUALS AND SPECIFICATIONS Standard Plans or Specifications The 34 agencies that currently perform or previously per- formed field welding were asked whether they have any stan- dard plans, specifications, procedures, or details for certain 20 59% 3 9% 11 32% In-house Contracted Out Both FIGURE 7 Staff performing field welding. FIGURE 8 Agencies with standard field welding plans, specifications, procedures, or details. FIGURE 9 Preparation of plans and specifications before welding. field welded repairs. Figure 8 displays the response to this question. A majority of agencies reported that they do not have this type of information for certain field welded repairs. Although most of the agencies do not have standard field welding plans or specifications, it was determined that the majority always prepare plans or specifications before per- forming field welding, as shown in Figure 9. No agencies ever require plans or specifications before field welding. Welding Code Requirements The 34 agencies that currently perform or previously per- formed field welding were asked whether they use a govern- ing specification or welding code for field welding projects. Figure 10 displays the responses to this question. Most agen- cies (27) responded that they “always” require a governing specification or welding code for field welded projects. The second most frequent response was that the use of a governing

23 specification or welding code was “sometimes” required. No agencies reported that they never require such a governing specification or welding code. Although most agencies require the use of a governing specification or welding code, the code most often specified by far is the AASHTO/AWS D1.5 Bridge Welding Code, as shown in Figure 11. Eighty-one percent of the agencies noted that they specify AWS D1.5, whereas only 13% responded that they specify the AWS D1.1 Structural Welding Code, which would be expected because the welding on a bridge com ponent in a fabrication shop would require that this code be followed. Two agencies choose “other” and further explained this choice: • Combination of D1.5 and internal standard specifica- tions and job special provisions. • NYS Steel Construction Manual. Base Metal Weldability Weldability is defined as the capability of a material to be welded under the fabrication conditions imposed and to perform satisfactorily in the intended service. The weldability of steel is often verified before field welding is initiated. Weldability is determined through review of the base material properties. The agencies were asked about the frequency of projects for which the base material properties were determined before field welding, and the results are shown in Figure 12. An identical number of agencies (14) responded that they either “always” or “sometimes” require base material property deter- mination before field welding. Five agencies responded that it was not known how often base material properties are deter- mined before field welding, and one agency responded that they never require base material determination before field welding. In a follow-up question, those agencies that responded that they either “always” or “sometimes” require base material properties to be determined before field welding were asked to select each of the following typical methods used: • Shop drawings, • Mill test reports, FIGURE 10 Use of governing specification or welding code. FIGURE 11 Governing welding code.

24 • Material samples, • Using date built information, or • Other (specify). This question was presented to 28 agencies and the results are shown in Figure 13. The most common method for determining base material properties was using date built information (20). The use of shop drawings, which generally includes information on the ASTM specification and grade of the steel, and the removal of material samples from the bridge for chemical analysis or coupon testing were the second most common at 17. Utilization of mill test reports, which include the chemical components of the heat of steel used in the man- ufacturing of the steel plates, was the least frequently cited method at 11. Four agencies also selected “other” and further explained as follows: • Design drawings, • As-built drawings, • Contract plans (mill test reports are not available on many old bridges), or • Plans. Unlike material sampling and the information provided in a Mill Test Report, the use of date built information and shop drawings will not provide the actual chemical makeup of the material. However, such methods can be effective in deter- mining the base metal weldability based on historical data or previous experience, but they replace true material sampling to determine base metal properties. When put in the context of the previous question, fewer than half of the agencies always determine base material properties before performing field welding. Two of the most commonly reported methods to determine base material properties do not involve testing of the actual base material. QUALITY ASSURANCE AND QUALITY CONTROL Qualification of Welders A review of welder qualifications is a common requirement in quality assurance and quality control programs. Such require- ments are specified in the applicable welding code. It was found that the large majority of agencies used welders certified according to the controlling welding code for the field weld- FIGURE 12 Base material properties determination prior to field welding. FIGURE 13 Methods to determine base material properties.

25 ing on their projects, as shown in Figure 14. Four agencies noted that it was not known whether the welders were certi- fied according to the controlling welding code and one stated that it did not use welders who were certified according to this code. Welding and Inspection Procedures A detailed welding procedure may be required by an agency before field welding to ensure that the contractor has made the appropriate preparations and accounted for job-specific requirements. Inspection procedures are often included in a quality assurance and quality control program and may be included in a bid package or with project specifications. The agencies were asked about the frequency that they require field welding procedures and/or inspection procedures before performing field welding. As shown in Figure 15, it was determined that the most common response was to “always” require field welding procedures and/or inspection procedures, followed by “sometimes” requiring these procedures. Five agencies responded that they did not know the frequency of projects that had these procedures submitted before welding, and one that it never required field welding procedures and/ or inspection procedures before performing field welding. In a follow-up question, the 28 agencies that responded that they either “always” or “sometimes” require field weld- ing and/or inspection procedures before field welding were requested to select one or more of the following items that are typically included in the field procedures: • Weld procedures, • Inspection procedures, • Welder qualifications, • Visual inspector qualifications (quality assurance and quality control), and/or • NDT qualifications (quality assurance and quality control). Once again, most agencies receive welder qualification as part of a field procedure package (93%) as shown in Figure 16. The second most frequently chosen item was weld procedures, followed by inspection procedures, NDT qualifications, and visual inspector qualifications, all used by at least 50% of respondents. Inspection Requirements Agencies were asked whether welding inspectors are required on site. For this question, no distinction was made as to whether these inspections occurred during or upon completion of the welding operation. Figure 17 shows the responses. Twelve agencies (35%) responded that they “sometimes” require on-site welding inspectors and 11 agencies (32%) that they “always” require on-site welding inspectors. Four agencies “never” require on-site welding inspectors for field welding projects. Typical NDT methods performed on field welds include surface techniques such as dye penetrant testing (PT) and FIGURE 14 Qualification of welders. FIGURE 15 Require field welding and/or inspection procedures.

26 magnetic particle testing (MT) and subsurface techniques such as ultrasonic testing (UT) and radiographic testing (RT). Agencies were asked whether NDT is required on field welds. No distinction was made regarding the specific types of NDT methods required. As shown in Figure 18, the most frequent response was that NDT is “sometimes” required on field welds (17), closely followed by NDT is “always” required (14). Only one agency responded that NDT is “never” required on field welds. PERFORMANCE OF REPAIRS AND RETROFITS The agencies were asked whether there have been any major problems associated with the repairs and retrofits specifically because they were field welds. This question was asked of all the agencies that answered that they either allow planned field welded repairs and retrofits or have previously per- formed field welded repairs and retrofits. Results are shown in Figure 19. Seventy percent responded that there have been no major problems associated with repairs and retrofits spe- cifically because they were field welds; six agencies that it was not known whether there have been any major problems because they were field welds, and only four agencies that they have had major problems specifically because they were field welds. In a follow-up question, the four agencies that had major problems with repairs and retrofits specifically because they were field welds were asked to select one or more of the following items that were at fault: • Premature cracking, • Improper welding, • Quality workmanship (good workmanship practices not followed), • Not installed in accordance with plans or specifications, and • Other (please specify). FIGURE 16 Information typically included with field procedures. FIGURE 17 Welding inspectors required on site.

27 FIGURE 18 NDT required. 6 18% 4 12% 24 70% Had Problems No Problems Unknown FIGURE 19 Agencies with projects that had major problems as a result of being field welded. FIGURE 20 Reasons for major issues with field welding. The most commonly reported issue with field welding was premature cracking, which was selected by three of the four agencies, and is shown in Figure 20. Improper welding and quality workmanship issues were the next most com- mon, selected by two of the four agencies. Installation not in accordance with the plans and specifications was selected by one agency. Further investigation was undertaken on the responses of the four agencies reporting major problems with repairs and retrofits specifically because they were field welds. All four currently allow planned field welding on their bridges. Also, all four use welders certified to internal requirements or the applicable welding code, and all four specify AASHTO/ AWS D1.5 Bridge Welding Code for their field welding proj- ects. Three of the four agencies reported that they contract out the welding, whereas one agency reported that it uses both in-house and outside contractor welding staff.

28 SUMMARY Forty-three agencies completed survey responses, an 86% response rate among state DOTs. The primary findings of the survey of the state of practice are summarized as follows: • Seventy-four percent allow planned field welded repairs and retrofits to be performed. • Of those agencies that do not currently allow planned field welded repairs and retrofits, only two have previ- ously performed field welding. • Six agencies provide case examples of field welded projects (see chapter four). • States as far north as Alaska, North Dakota, Minnesota, and Maine allow field welding: – There does not appear to be a correlation with lowest anticipated temperatures and general geographic loca- tion and the propensity for field welding. • Quality of work was the most common reason chosen for why agencies do not allow field welding. • Most agencies contract out their field welding projects. • Most agencies require the use of a governing specification or a field welding code: – 81% that require a weld code specify AASHTO/ AWS D1.5 Bridge Welding Code. – 13% that require a weld code specify AWS D1.1 Structural Welding Code, although AASHTO/AWS D1.5 is specifically developed for bridge welding and is specified for bridge fabrication. • Fewer than half of the agencies reported that they always require base material property determination before field welding: – The most common method for determining base material properties involved the use of date built information. – The use of shop drawings and removal of material samples were the next most common method to determine base material properties. – Use of date built information and shop drawings will not provide the actual chemical makeup of the material. • It was found that the large majority of agencies used welders certified according to the controlling welding code for the field welding on their projects. • Less than one-third of the agencies always require welding inspectors, including for inspections that may not be performed until after the welding process has been completed. • Seventy percent noted that there have been no major problems associated with repairs and retrofits specifi- cally because they were field welds. • Only four agencies mentioned that they have had major problems with repairs and retrofits specifically because they were field welds. – The most common issue with field welding was premature cracking, selected by three of the four agencies. – Improper welding and quality workmanship issues were selected by two of the four agencies.