[MODULE 11 PART 2] ASME PCC-2 (2018) - API 570 STUDY GUIDE

                                                        ASME PCC-2 : 2018

Repair of Pressure Equipment and Piping

API 570 STUDY GUIDE

PART 2

Part 1 of this Series:

https://hareeshkv.blogspot.com/2022/11/API570MODULE11PART1-ASMEPCC-2-2018.html

Here we will go through Article 201 of ASME PCC-2

Part 2 : covers repair methods and techniques that include the use of welding, brazing, soldering, or other methods involving metal deposit.

Article 201: Butt-Welded Insert Plates in Pressure Components

The repair method discussed here is "replacement of pressure boundary material in a pressure component with an insert plate attached by full penetration butt welds."

Points to be noted.

1. Practically possible any profile of the pressure component can be repaired by this method.
2. Corrosion-Resistant Weld Overlay or Cladding, dissimilar metals are also repaired using this method. 
3. Portions of the pressure retaining walls are replaced in this method. 
4. The replaced areas may contain nozzles also.
5. Replacement of an entire component is not in the scope of this repair method.
6. All the considerations in the original design of the component should be done in this repair method also, like material of construction, strength, impact strength etc.
7. Other than the original design considerations the following are to be considered in the repair method
• Limitations in the NDT applicability if any for the repaired area
• Limitations in pressure testing if any covering the repaired area
• If the pressure component is subject to external pressure, additional consideration shall also be given to any loss of buckling strength as a result of permanent distortions or misalignment
• In the repaired component, if the pressure component is subject to cyclic loading, additional consideration shall be given to the effect of permanent distortions on the fatigue life of the repaired component.
8. Use of dissimilar materials (base metal and welds) is not prohibited, but the materials shall meet the required minimum mechanical properties for the pressure component and shall be carefully evaluated for compatibility between the dissimilar materials and the service environment, both internal and external. If thermal fatigue is a possibility, consideration shall be given to the potential for accelerated fatigue cracking in the dissimilar metals combination.
• Explanation: This means that dissimilar materials can be used for this repair method. That is other than the original MOC of the parent material component and weld can be used for this repair method subject to the conditions mentioned.
9. Before making a cutout, structural stability of the component after the cutout should be evaluated. Temporary supports may be required to the vessel before making cutouts.

INSERT PLATE

1. Design: The insert plate thickness, material, welds, joint efficiency, joint quality factors should be same as original design code of the equipment. 
• Explanation: This means that if a vessel is designed and constructed based on ASME BPVC Sec 8, all the design parameters should be followed based on ASME BPVC Sec 8. If a piping is designed based on ASME B31.3 then all the parameters and considerations of ASME B31.3 is to be used for the repairing of piping. In general the design considerations in the original construction code and design code are to be followed other than that mentioned in this code.
2. Material and welding for insert plate: Same as the existing pressure component. If another material is to be considered then it should have atleast equal notch toughness and allowable stress of the parent material but should confirm to the applicable requirements of the construction code and should be suitable for the intended service. Same ASME P number material should be used.
3. Insert Plate Thickness : Should not be less than the nominal thickness of the material it welds into. If a thinner material is to be used, evaluation for the intended service based on original construction code to be done.
4. Shape of insert plate: Rectangular, Square, round or oblong cutouts. For rectangular and square cutouts the corner should be rounded as follows
• Plate thickess <13mm : May have smaller corner radius
• Plate thickness: From 13mm to <=25mm : 75mm or a larger corner radius
• Plate thickness >25mm : 150mm or a larger corner radius
5. Size of the insert Plate: Lesser of 12t or 380mm, 't' is the thickness of the parent material.

Click Here for Further Reading on this series

This blog is not a replacement for the training provided by authorized partners/experienced institutions nor this blog guarantee success in API exams. This blog is the outcome of the approach followed by the author for the preparation of API exams. 

Disclaimer: Photos are taken from different websites. If this violates any copyright rules this will be removed. Please inform me if any of the photos or contents violate copyright rules. (through 13hareesh13@gmail.com). This blog is meant for educational purposes only. If it is used for any other means without the written consent from the author, the author will not be responsible. The author does not guarantee the accuracy of the data used in this blog. All the information, data, photo/image, calculations presented in this blog should be used at the sole risk of the user. The blogger is not liable or responsible in any way for any damage, losses or costs arising from the use of the blog for any purpose whatsoever or whosoever it may be. The blog is to be used at your sole risk and responsibility.