Summer is here, and you need to adjust for the temperature change.
Installing pipe relining and not knowing what the temperature of the resin is can be a disaster. If you take a summer day temperature in the mid 30’s, and factor in a cold front that comes through and makes life liveable again (in fact, it dropped to 18 degrees last night, and sleeping was great), the results can be challenging to measure.
The liner for today was easy: 20 metres from pit to pit and 100mm all the way, so you figure the resin should have cooled off to the overnight low of 18 degrees as it was stored in the workshop. You need 20kg of mixed resin (hardener and base). By the time you get to the job, the temperature outside was 23 degrees, and you’re in store for a beautiful day.
As it wasn’t hot, you sit the pails of resin near the scale that was sitting in the sun and continued on with preparing the job site. You had everything cleaned, and ready to line and it wasn’t 10 AM yet. The liner was measured, cut, and you were ready to start mixing the resin. Since it wasn’t hot, you forgot about the shade canopy, poured the base resin on the scale, and added the hardener. Got the mixing bit in the pail and began mixing, you picked up a 30-minute resin hardener and mixed it for the three minutes as called for. You poured the mixed resin into the tube and began wetting out. But after you got 10 metres of the tube wetted out, the remaining slug was getting warm. Wait, what? How could it be? It was only 23 degrees, and while we didn’t chill the resin, it must have been less than 20 degrees. Wasn’t it?
Well, it wasn’t less than 20 degrees. In fact, it must have been well over that. You were sure this was going to be an easy day, easy job, and home early. Needless to say, by the time you got the last metre wetted out, the tube was very hot and starting to cure. There was no way you were going to get this in the ground.
This is the time the blame game begins, surely the resin supplier gave you mislabelled 15-minute resin instead of the 30 minutes? But you still should have been okay, because you were well within 15 minutes between mixing and this point in the “wet out”. Did your offsider keep the resin in the shade from the time you picked it up? It was a little warm in the van, but there was no sun where you stored the resin on the job while you cleaned the pipe? Oh! You remember sitting the hardener and base in the sun on the job site. But it couldn’t heat it up that much that fast when it is only 23 degrees? Yes, the workshop was boiling when you got in yesterday afternoon, but the resin should have cooled as quickly as the air temperature, shouldn’t it?
After trying to find someone to blame for this disaster, you finally realised that the one to blame was yourself! You should have had a thermometer and measured the resin temperature. Thankfully you had enough supplies to redo the job but had to get the resin cooled down. The workshop wasn’t that far away, so you made a quick trip back to get a thermometer, a tub and some ice to cool the resin. While there, you checked the bucket temperatures in the workshop – the same resin that you had taken the resin from. The temperature outside of the bucket was 27 degrees. Upon inspection of the label on the hardener, at 27 degrees you have 20 minutes working time, 10 minutes less than three degrees cooler. Wonder how much time at 30 degrees? Maybe 5-10 minutes!
You didn’t manage the resin temperature because you didn’t take the temperature of the material until it was too late. Lesson learned! Never assume the temperature, no matter what, never ever. If three degrees can cut working time by 33%, you need to know where you’re at and how much time you have left.
One final thought – you worked the resin in the sun, and you’ll remember that UV light will speed up the curing process as well. To have been successful with your liner you should have used the canopy, taken the temperature of your resin and controlled the temperature of your resin – otherwise it can be a disaster, and you’ll have to do the job over again.