Annex B In-service Welding- CWI Part C

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Annex B In-service Welding – CWI Part C Practice Test

Prepare for the AWS CWI Part C Open Book Exam with this free practice test based on API 1104 Annex B: In-service Welding. This annex is important because it explains welding practices for repairs and appurtenance installation on piping systems that are already in service.

In this quiz, you can take a free practice test with the latest exam-style questions and answers for CWI Part C API 1104 Annex B In-service Welding.

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This free quiz is designed for AWS CWI candidates, welding inspectors, QA/QC inspectors, pipeline welding professionals, NDT personnel, and students preparing for the AWS CWI Part C exam using API 1104.

Annex B focuses on in-service welding, hydrogen cracking prevention, burn-through risk, procedure qualification, welder qualification, inspection, testing, acceptance standards, and repair requirements.

Quiz Details

Quiz Name: Annex B In-service Welding – CWI Part C
Standard Covered: API 1104
Exam Type: AWS CWI Part C Practice Test
Total Questions: 9 Questions
Question Type: Multiple Choice Questions
Level: Exam Preparation Level

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What Is Covered in API 1104 Annex B?

API 1104 Annex B provides guidance and requirements for welding on piping systems that are already in service. These welds are commonly used for making repairs or installing appurtenances on operating pipelines.

In-service welding is more critical than normal welding because the carrier pipe may contain flowing fluid. This flowing fluid can remove heat rapidly from the weld area, increasing the cooling rate and creating a higher risk of hydrogen cracking.

Main Risks in In-service Welding

Welding attachments onto in-service pipelines creates two major risks:

• Burn-through of the pipe wall
• Hydrogen cracking

Burn-through is less likely when wall thickness is 0.250 inch or greater, but it still requires careful control. Hydrogen cracking is the main focus of Annex B because in-service welding conditions can promote rapid cooling and crack-sensitive microstructures.

Hydrogen Cracking in In-service Welding

For hydrogen cracking to occur, three conditions must exist at the same time:

• Hydrogen in the weld
• Crack-susceptible microstructure
• Tensile stress acting on the weld

In in-service welding, hydrogen may be present, and residual tensile stress is normally created during weld shrinkage. Therefore, the main method of preventing hydrogen cracking is to prevent the formation of a crack-sensitive microstructure.

This is usually done by using a welding procedure with enough heat input to overcome the quenching effect of the flowing fluid. Temper bead welding may also be used to produce a more hydrogen-crack-resistant heat-affected zone.

Types of In-service Welds

Annex B discusses welds that melt into the carrier pipe, including:

• Fillet welds
• Branch connection welds
• Sleeve welds
• Circumferential welds

Fillet welds are often used to join the ends of encirclement sleeves to the carrier pipe. Groove welds may be used to join split sleeves using longitudinal welds, but these welds do not melt into the carrier pipe in the same way as sleeve welds and branch connection welds.

Qualification of In-service Welding Procedures

In-service welding procedures are qualified using the basic requirements of API 1104 Section 5, with the additional requirements and exceptions given in Annex B.

The procedure specification must include additional information, such as:

• Carbon equivalent of the carrier pipe
• Pipeline operating conditions
• Fluid type and flow rate
• Heat input range, when heat input is used to control cooling
• Temper bead sequence, when temper bead welding is used
• Bead size and overlap for temper bead procedures
• Heat input range for each temper bead layer

These details are important because in-service welding procedures must control cooling rate and hydrogen cracking risk.

Carbon Equivalent

Annex B uses carbon equivalent to evaluate hardenability and hydrogen cracking risk.

The carbon equivalent formula given in Annex B is:

CEIIW = %C + %Mn/6 + (%Cu + %Ni)/15 + (%Cr + %Mo + %V)/5

An increase in carbon equivalent over the value used during procedure qualification is an essential variable. This means the carrier pipe used for the qualification test should ideally have a high carbon equivalent so that the procedure qualifies a wider range of production pipe materials.

Essential Variables for In-service Welding Procedures

Annex B modifies the essential variable rules from Section 5.

For in-service welding:

• SMYS is no longer an essential variable
• In-service welding procedures may be valid for all pipe grades
• Increase in carbon equivalent is an essential variable
• Pipeline operating condition severity is an essential variable
• Lower heat input than that used in qualification may require requalification
• Change in temper bead deposition sequence or bead overlap may require requalification

For in-service fillet and branch welds, pipe wall thickness is generally not an essential variable. However, for weld deposit repairs, the procedure is qualified only for wall thicknesses equal to or greater than the wall thickness used in the qualification test.

Qualification Test Joint

Annex B procedure qualification uses a test coupon that simulates the cooling effect of flowing contents inside the pipe.

A common test setup uses a carrier pipe filled with flowing water, with a sleeve or branch connection welded to it. This condition produces severe thermal conditions and helps prove that the procedure can resist rapid cooling conditions found in service.

A procedure qualified under this severe condition may qualify for typical in-service applications.

Testing of In-service Welding Procedure Qualification Joints

In-service welds that melt into the carrier pipe are generally tested using nick break tests, along with additional tests required by Annex B.

Testing may include:

• Nick break tests
• Macro section tests
• Face bend tests
• Hardness testing
• Visual examination of macro-etched specimens

Longitudinal seam welds of full-encirclement sleeves are tested using tension tests, bend tests, and nick break specimens according to the applicable Section 5 requirements.

Macro Section Tests

Macro section specimens are removed from in-service branch and sleeve welds.

The specimens are ground, polished, etched with a suitable etchant, and visually examined with little or no magnification.

The macro section examination checks important weld quality points, including:

• Complete fusion at the root of the joint
• No cracks
• Fillet weld leg size meeting procedure requirements
• Acceptable fillet weld surface profile
• Undercut within permitted limits
• HAZ hardness evaluation where required

Hardness testing is performed using ASTM E384. At least five indentations are made in the coarse-grained heat-affected zone at the toe of each weld cross-section using a Vickers indenter and a 10 kg load.

HAZ hardness values above 350 HV should be evaluated for hydrogen cracking risk.

Face Bend Tests

Face bend specimens are also required for in-service welding procedure qualification.

These specimens may be cut separately, or the remaining portion of nick break specimens may be used. If oxygen cutting is used, the specimen must be machined by a nonthermal process to remove affected material from each side.

Face bend specimens must not be tested sooner than 24 hours after welding.

The acceptance criteria for these bend specimens are the same as the bend test criteria in API 1104 Section 5.

In-service Welder Qualification

Welders performing in-service welding must qualify by making a single qualification test weld according to API 1104 Section 6.2, using the specific in-service welding procedure.

The welder may qualify using:

• Heat input procedure
• Temper bead procedure
• Weld deposition repair procedure

If the qualification test is performed on pipe less than 12.750 inches OD, the welder is qualified for pipe diameters up to and including the diameter tested.

If the qualification test is performed on pipe 12.750 inches OD or larger, the welder is qualified for all pipe diameters.

Multiple Qualification for In-service Welding

A welder who meets both the multiple qualification requirements of Section 6.3 and the additional qualification test requirements of Annex B may be qualified as an in-service branch or sleeve welder.

For weld deposition repairs, the welder qualification may be limited based on the positions used during the qualification test.

Welder qualification test coupons should simulate the cooling effect of flowing contents, commonly by using flowing water inside the carrier pipe during welding.

Suggested In-service Welding Practices

When performing in-service welding, the requirements of API 1104 Section 7 apply, along with the additional practices in Annex B.

Safety is the primary concern. Important factors include:

• Operating pressure
• Flow conditions
• Minimum wall thickness in the weld area
• Pipe wall condition
• Presence of laminations
• Suitability of the welding area

Ultrasonic testing is commonly used before welding to determine minimum wall thickness and verify that no laminations are present in the pipe wall.

Additional safety practices may also be found in API Recommended Practice 2201.

Alignment and Fit-up

For saddle and sleeve welds, the gap between the sleeve and carrier pipe should be minimized to allow proper fusion into the carrier pipe.

Clamping devices are recommended.

For longitudinal butt welds of full-encirclement sleeves, the root opening should allow full penetration. A mild steel backup strip or suitable tape may be used to help prevent penetration into the carrier pipe.

Welding Sequence

The welding sequence should be selected to minimize residual stresses.

For full-encirclement sleeves requiring circumferential fillet welds, longitudinal seams should be completed before starting the sleeve welds. When welding circumferential fillet welds, one sleeve weld should be completed before starting the other.

Heat input limits, temper bead sizes, and temper bead locations must follow the approved welding procedure.

When possible, in-service weld beads should be deposited in the circumferential direction.

Inspection and Testing of In-service Welds

In-service welds must meet the inspection and testing requirements of API 1104 Section 8, along with additional or alternative requirements from Annex B.

Because hydrogen cracking is a major concern, the inspection method must be capable of detecting underbead cracks and toe cracks.

A combination of magnetic particle testing and ultrasonic testing is recommended for sleeve-to-carrier, saddle-to-carrier, and branch-to-carrier pipe welds.

Radiographic testing is not considered a good method for detecting these types of cracks.

Delay Time Before Inspection

Hydrogen cracking may take time to develop after welding.

Because of this, a suitable delay time should be established before final inspection. This helps ensure that inspection is performed after any hydrogen cracking has had time to appear.

This is an important point for CWI Part C candidates because inspection immediately after welding may not always detect delayed hydrogen cracking.

Standards of Acceptability

The standards of acceptability in API 1104 Section 9 apply to imperfections in in-service welds.

For weld deposition repair, the weld length is defined as the maximum weld length in the direction in which the flaw is oriented.

Repair and Removal of Defects

The repair and removal requirements of API 1104 Section 10 apply to in-service weld defects.

Additional care must be taken during excavation of defects. The repair excavation must not reduce the pipe wall thickness below the minimum required to contain the pipe’s operating pressure.

This is a critical inspection and safety point for in-service welding.

What You Will Learn in This Quiz

This practice test will help you understand:

• Purpose of API 1104 Annex B
• In-service welding risks
• Burn-through and hydrogen cracking
• Conditions required for hydrogen cracking
• Heat input and temper bead control
• Qualification of in-service welding procedures
• Carbon equivalent calculation
• Essential variables for in-service welding
• Procedure qualification test coupon requirements
• Macro section testing
• Hardness testing requirements
• Face bend testing requirements
• In-service welder qualification rules
• Suggested in-service welding practices
• Alignment and fit-up requirements
• In-service weld inspection methods
• Delay time before inspection
• Acceptance standards for in-service welds
• Repair and removal requirements

Why Practice Annex B In-service Welding?

Annex B is an important topic for the AWS CWI Part C exam because it covers welding on operating pipelines. These welds require special control due to burn-through risk, rapid cooling, hydrogen cracking, and pressure-retaining safety concerns.

Practicing Annex B questions will help candidates understand in-service welding procedure qualification, welder qualification, inspection requirements, and special safety considerations.

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Quiz – Annex B In-service Welding – CWI Part C – 9 Questions
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Who Should Take This Practice Test?

This quiz is useful for:

• AWS CWI exam candidates
• CWI Part C API 1104 students
• Welding inspectors
• QA/QC inspectors
• Pipeline welding professionals
• NDT technicians
• Welding supervisors
• Welding engineers
• Students preparing for open-book code exams

Prepare Better for AWS CWI Part C

If you are preparing for the AWS CWI Part C exam, Annex B In-service Welding is an important topic to practice. It explains how in-service welding procedures and welders are qualified, how welding is performed safely, and how in-service welds are inspected and accepted.

Take the free practice test now and improve your preparation for the AWS CWI Part C API 1104 exam.

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