FRP Lamination StudyPoor Preparation of FRP Lamination Surface and Solution

Due to Poor Preparation and Lamination, our client had issues with leaks at the scrubber to inlet joint area visible in the photo to the left.





Our initial hypothesis is best explained by the simple graphic below.













Lamination Penetration Discovery Phase

Upon arrival at the site we noted signs of poor lamination which prompted
a series of grinding steps to reveal liquid penetration points.


Signs of poor lamination.


Liquid appearing from inside the joint.

After 2nd Grinding More Liquid is Revealed Inside Joint

Grinding Reveals More Penetration

Evidence of liquid inside joint.

Chemical Inside FRP Joint

Liquid draining from joint.

Leak Penetration Point Found












Lamination over post peeled off easily with light prying due to poor surface preparation.

Leak Path After Penetration Point Found

There was no lamination of the wall to inlet directly behind the post. The post installation technique should have been:

  1. Laminate to seal off inlet to scrubber wall joint (putty & laminate) – only putty was used.
  2. Place post and put a laminate over the post.
Leak Path Found in FRP Joint

After 3rd grinding the bottom of the middle post was cut 6″ from bottom.

Laminate Sealing

It was noted that there was no laminate directly behind the post (bad)

Joint Liquid Infiltration

Liquid pouring out of joint, due to similar issue as above.

Liquid Inside Joints

Further grinding revealed a lot of liquid inside the post to wall joint.


Repaired FRP Joint with Large Patch

frp-coatings-applied-to-postFRP Lining Repairs Made

  1. Cut post ~6″ from bottom.
  2. Surface preparation to obtain good adhesion.
  3. Seal off inlet to wall joint (at bottom of inlet)
    1. Laminate joint from inlet to scrubber
    2. Bottom horizontal joint.
    3. Minimum 4′ on the vertical joint.
  4. Install Post – Post to scrubber wall connection at inlet
    * Due to the leaks, a conservative approach was used in
    designing the repair patches. Posts, made of pultruded
    FRP, which is harder to adhere to, at least 4′ along the
    post height was grinded.