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Fitting up blast hose to a blast pot with a pressure hold deadman system

BlastOne’s Master Technician, Kerry Cooper, shows fitting up a blast hose to a blast pot coupling

 

So, on the end of the Thompson valve here, we have a coupling. This is called a brass thread and coupling the brass threaded coupling is normally put on with a bit of threat tape, primarily because, we have to make sure that it’s sealed.

What can happen is if that’s not sealed? The abrasive can mix with the air that escapes out where it’s not sealed on the thread and undermine the integrity of the thread and the coupling itself.

Now, here’s an important note, in this coupling is a small thing called a gasket. It’s imperative that this gas gets checked every day or at the end of each blasting day, you check the gasket for its concentric value.

The face of each side of the gasket and also, if the gasket has been under stress, it’ll tend to cut one side out of the gasket and you say it quite clearly where it’s been undermined as far as its wall strength or face is concerned. So. this gasket is checked every night.

How does this gasket become undermined when it’s stuck in something like that that’s sitting still?

It’s relatively simple. The blast hose that attaches to this, you can say also that this is a claw coupling that attaches to this particular fitting like so.

So, in this guest, this fitting as well this is a long series coupling, it has another gasket Now, this gasket here has to marry that one there to seal it — to seal the air stop the air and grit coming out of the fitting. It also has two holes in there for a safety clip.

Safety clips in this particular item are mandatory. On the blast hose itself, one clip is not adequate. There’s two holes utilized — the two holes with two clips. Clips are mandatory whip checks. Mandatory so the whip check goes on to the primary fitting. It’s extended out with no slack on the secondary section.

So, with this gasket, in this gasket by coupling these two together. First, what I’ll do is I’ll put my whip check and slide it underneath so it’s out of the way. Bring your hose around and twist that coupling on there. Now, if you have this hose twisted up, you’ll find that it’ll want to twist back all the time. So, I’ll appropriate the hose to take the torque off the hose so it twists back onto that coupling easily.

Now, if I put two pins in there and for this exercise, I’ll just put the one. So, if I put the two pins in, what I’ll find is that it holds that coupling nice and still. However, if you don’t have a nice big long radius on this hose and you pull the hose around like so, you can see here that starling create a restriction in the hose but consequently what it’s doing is it’s creating unnecessary talk or thrust on these gaskets inside.

So, by pulling it around like that, that’s putting torque on those particular gaskets. So, what that does is that the gasket is no longer seating square. So, to put it in realistic terms for you, if you twist that hose to one side, this gasket here is squashed down that side and lifting up that side. So, ultimately, the air will start to pass through that gap and cut those gaskets out relatively quickly.

If it starts cutting the gasket out the recess in this fitting, and the claws and the face edge are all undermined by the escaping air, and the consequential grit that comes with it.

So, not only to undermine the safety aspect of this particular fitting, premature wear unnecessary replacement of this, primarily because, the grit has attacked all the parent metal as well as the gasket. You need to replace it because it’s deemed unsafe if you leave that and it’s escaping air and grit. The consequence is someone can get hurt.

Also, what happens is that the air and the grit escaping can be per-directional to the frame, to the ground, to the operator, to the pot tender also, to the pot itself.

So, the grit can actually continue to blast the bottom of the pot and ultimately, will undermine the integral wall strength of this particular pressure vessel.

So, remember it’s a pressure vessel. It has to be compliant. You cannot weld to this. You cannot put extra lugs on it. You can’t weld a hole up if it is the consequence of escaping air and grit. It is a pressure vessel if you’ve undermined the integrity of the wall of the pressure vessel. It’s deemed unusable.

So, of course, with this particular item comes the two hoses primary signal hose return airline hose. So, these two attached to the back of the pot where the pilot valve is.

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