Installation and Troubleshooting problems Associated with Isoalation Flanges October 2018 Nick Bander Engineering Manager

Transcription

1 Installation and Troubleshooting problems Associated with Isoalation Flanges October 2018 Nick Bander Engineering Manager 1

2 Agenda Isolation kit installation Proper Installation Procedure Bolt torque Isolation Check Case Studies of Improper Installations 2

3 Installation Instructions 1/2 3

4 Installation Instructions 2/2 4

5 What do you guys think? What is the Most Critical Factors of Installing an Isolation Kit? 1. Flange condition and preparation 2. Flange Alignment 3. Torque Up 5

6 Preparing Flanges for Installation Recommended Arithmetic Average Roughness Height (AARH) Properly clean the flanges Inspect for previous corrosion and machine if necessary 6

7 AARH Surface Finish 1/2 Typically standard on ASME Ideal surface roughness is micro inches Serrating will bite into the seal and retainer material API 6A and/or RTJ flanges have SMOOTH FACES Why? The serrations bite into the gasket face and seal, locking it into place 7

8 AARH Surface Finish 2/ micro inch has enough bite without being too aggressive 500 micro inch is too aggressive for the gasket and seal Note: not to scale 8

9 Clean the Surface of the Flange Face Use Scotch Brite or a wire brush to clean the face of a flange Removes previous corrosion 9

10 Residue Needs to be Removed Flange with Metallic Debris Gasket with Corrosion Residue Flange Flange Face Oxidation and Debris Gasket Flange debris and oxidation can allow Oil can migrate past seals 10

11 Flanges Shall Be Cleaned Prior to Install Uncleaned Flanges can cause a breach in the coating and decrease in isolation or worst and impact to sealing performance. 11

12 Isolation Washer Failure Failed MICA Washers Sheared GRE Washer 12

13 Flange Face Condition 13

14 Flange Face Conditions Catastrophic Release of High Velocity Gas 14

15 Case Study Application # Good 125 AA finish Sweet Gas Clean Flange Gouges on flange sealing area Catastrophic Release after 4 months 15

16 Flange Alignment Axial Alignment Parallel flange faces Bolt holes Gap between flanges 16

17 Flange Alignment When are flanges aligned? Isolation sleeve 1/8 (3.2mm) clearance between bolt OD and hole ID 1/32 (0.8mm) sleeve wall thickness 1/16 (1.6mm) maximum clearance 17

18 Gasket Installation Gap between flanges is critical, it should be ~1.5x the gasket thickness. Protect the gasket while lowering in place. Assure proper alignment before lowering gasket in place Seals can be damage or pulled out Damaged seals will not hold pressure Coated gaskets and gasket components Damaged coating will not isolate 18

19 Installing with Hammer and Pry Bars 19

20 Aligning Flanges with the gasket in Place Alignment Pins and Spreaders are good tools but they need to be used to achieve alignment before the gasket gets lowered into place. 20

21 Flange Alignment Video - How not to align flanges 21

22 Bolt Assemblies/Sleeves Purpose of Isolation Sleeve Sleeve Length is calculated to includes EVERYTHING that the sleeve will go past or through. Flanges Gaskets Washers Any thing else SLEEVE LENGTH 22

23 Bolt Assemblies/Sleeves Sleeve Length Calculation: What is different? Do I need a special calculation? SLEEVE LENGTH 23

24 Sleeve Length Too Short/Long Sleeves that are too short can cause isolation loss across the assembly from bolt to flange contact Sleeves that are too long can crack sleeve and cause short or resist torque leading to a decrease resultant gasket stress 24

25 Are Washers in the Right Order? Whats Wrong? Have you seen this before? 25

26 Gasket Centering Install bolt assemblies on lower half of flange Bolt lubricant Isolation washer Steel washer nut Note: Gasket is centered by bolt sleeves 26

27 Installing the gasket before aligned This Company lowered the gasket in place before they were align and supported They cracked two gaskets before getting it right They had to wait 1 week for each replacement 27

28 Isolation Kit Assembly Complete Install remaining bolt assemblies in flange Bolt lubricant Isolation washer Steel washer nut 28

29 Flange Torque Up 29

30 What to Consider Before Selecting Torque Flange Size and Pressure Rating Gasket Type Assembly Materials Flange Materials Bolt Materials Are you using lubricant or Coated bolts 30

31 Installation Instructions Torque in Ft-lb Torque in N-m 31

32 Torque Table Notes 2. All values have been calculated assuming a 0.16 Coefficient of Friction and new nuts and studs. For PTFE or Xylan coated studs use the recommended values shown here. 32

33 Torque Pattern 33

34 Incorrect Assembly Torque Failure due to over torquing the gasket Too much stress on the GRE where the OD of the raised face sat Over-rotation of the flange 34

35 Incorrect Assembly Torque Applied torque needs to be translated to proper gasket seating stress How? 35

36 Incorrect Assembly Torque Bolt coefficient of friction is a HUGE factor for gasket seating stress. 36

37 Incorrect Assembly Torque 3/6 The flange rotated enough that it caused the gasket GRE to fail. This means there had to be over 60,000 psi of stress. (Normally aiming for 7500 psi) 37

38 Non Uniform Seating Stress Too much seating stress can cause issues There was not clear record grooving around the entire gasket VCFS carbon back up ring can smash the stainless steel underneath it Uneven flange faces also caused this failure 38

39 Electrical Isolation Testing RF (Radio Frequency) isolation tester Ohm-Meter Potential (voltage) measurements with reference electrode 39

40 Isolation Testing Testing With or Without CP Testing With CP Only 40

41 NACE SP-0286 on the use of an ohmmeter 41

42 Isolation Testing RF Tester and Ohm-Meter Flange-to-Flange Flange-to-Bolt Flange-to-Gasket Core 42

43 Recap Common Failure Modes of Installation 1. Lowering the gasket in before allignment 2. Non Uniform Seating Stress 3. Incorrect assembly torque 4. Debris on the Flange Face 5. Isolation washer failure 6. Installing gaskets against another gasket 43

44 Dual Gasket Installation A spiral wound gasket was installed with this VCFS This caused cupping of the gasket DO NOT INSTALL WITH OTHER GASKETS 44