MAHMOUD T.Inspection Engineering Tools
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Gasket Seat Surface Inspection

Field inspection guide & multi-defect acceptance calculator

1. Acceptance Criteria

Radial positionHard-faced
max depth		Soft-faced
max depth
rd < w/4< 0.76 mm< 1.27 mm
w/4 < rd < w/2< 0.25 mm< 0.76 mm
w/2 < rd < 3w/4Not allowed< 0.13 mm
rd > 3w/4Not allowedNot allowed

2. Defect Evaluation

Gasket type
Hard-faced
Need help choosing?
flange / equipment tag or ID
mm • radial width of gasket seating surface
Required — enter the gasket seating width before evaluating defects.
Defect #1
Required — Enter Radial Len. rd.
Required — enter depth d.
Defect photo preview
PENDING — Missing required data — gasket seating width (w), radial length (r_d), depth (d).
Total Defects0
Accepted0
Rejected0

Defect Summary

#TypeOrientationrd (mm)d (mm)rd/wZoneStatus
Inspection Report 







3. Defects Figures Reference




                        

                            Figure D‑3‑1 – Projected radial width of defect
                        

                        

                            

                        










4. Field Guide




    
    


        

            

                
Gasket Type Classification

            


            
                HARD / SOFT-FACED
            
        


        

            Use the gasket construction to select the appropriate
            Hard-faced or Soft-faced category
            before applying the PCC-1 flange seating-surface defect limits.
        



        


            
            


                

                    S

                    

                        Soft-faced
                        Use the Soft-faced criteria
                    

                


                
    
                    
  • 
                        Spiral-wound + graphite
                        Soft-faced
                    
    • 

                    
  • 
                        Spiral-wound + PTFE
                        Soft-faced
                    
    • 
                


            



            
            


                

                    H

                    

                        Hard-faced
                        Use the Hard-faced criteria
                    

                


                
    
                    
  • 
                        Flat solid metal gasket
                        Hard-faced
                    
    • 

                    
  • 
                        Ring-type joint (RTJ)
                        Hard-faced*
                    
    • 

                    
  • 
                        Flat metal-jacketed gasket
                        Hard-faced
                    
    • 

                    
  • 
                        Double-jacketed gasket
                        Hard-faced
                    
    • 
                


            


        

    



    
    

        

            ① Measure w
            Determine the radial width of the gasket seating surface.
        


        

            ② Measure rd
            Use the projected radial distance across the seating surface.
        


        

            ③ Measure d
            Measure defect depth from the peak of the surface finish to the bottom.
        


        

            ④ Evaluate
            Compare the defect with its radial zone and gasket classification.
        

    



    
    

        Important:
        rd is the projected radial width of the defect
        across the gasket seating surface. It is not the
        circumferential length of a scratch, gouge, pit, or dent.
    



    
    
Pits and dents — joined defects


    

        For joined pits where the spacing
        s ≤ rdi, use the applicable combined radial
        dimension:
        rd = Σrdi.
    



    
    
Scattered pits


    

        For scattered defects, the radial dimension is evaluated as the sum of
        the applicable individual projected radial widths, as illustrated in
        Figure D-3-1.
    



    
    
Surface preparation


    

        Do not locally polish, grind, or buff the gasket seating surface.
        Remove burrs only, unless an approved engineering / repair procedure
        specifically permits otherwise.
    



    
    
Important Additional Requirements


    


        

            Minimum Finished Raised Face Height:
            The final, post-machined raised face height must not be less than
            0.8 mm (0.031 in.).
            Standard original raised face heights are
            1.5 mm (0.06 in.) for Class 150/300 flanges, and
            6.4 mm (0.25 in.) for Class 400+ flanges.
        


        

            Surface Finish for Gaskets:
            For spiral-wound, soft-faced metal core, and grooved metal gaskets,
            a serrated concentric or spiral finish should be provided with a
            roughness of
            3.2 to 6.4 µm Ra (125 to 250 µin).
        


        

            NDT Requirements:
            Prior to performing any weld buildup, verify the soundness of the
            base metal. After completing any weld buildup and subsequent final
            machining, perform Liquid Penetrant (PT) or
            Magnetic Particle (MT) examination on the finished
            surface.
        


    










5. Field Checklist



    

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