The pig in a pipe :-)

Woo hoo, almost 6:30 and I could have actually stayed in bed a little longer had I wanted It was only the fact that I’d made up my mind yesterday to write a few lines on here afore going ‘back under the bug’ that stopped having an extra hour. Of course the ‘Shy Pig’ that I found in the car helped.

A kind neighbour donated the bottle last week ‘for services rendered’ it wasn’t actually necessary but was welcome after a ‘hard days pigging’ Well there’s a new one for you hey and the pig I’m talking about had a flat face no legs and came from here http://pipelinepigging.co.uk/ to do this https://en.wikipedia.org/wiki/Pigging 

Yesterday’s project was to help a friend of mine clean another friends turbine penstock for his 15kW 90 year old Gilkes  http://www.gilkes.com/Hydropower hydro scheme. It’s one of the these schemes of which their were plenty of in the Highlands and Islands before electrification. When just about every large estate in the highlands had one supplying ‘the big hoose’. As was the case with a lot of them it fell into disrepair and was abandoned once the grid arrived in the seventies.

This particular one, again like many, was also resurrected in the noughties in an attempt to stem climate change. The old cast iron penstock being dug up and replaced by 280mm MDPE and the DC generator being replaced by a three phase one. The actual 90 year old cast iron turbine though is still the original and Gilkes still have all the information on it!!!

So, on what was a beautiful morning that went rapidly downhill I set off to get the 8:55 and off we went in the pishing rain to Talisker on Skye.

  

The first task being to shut off the water intake, which on this particular installation is not very easy. Whilst the installer made a fine job of the dam ‘Coanda screen’  https://en.wikipedia.org/wiki/Coand%C4%83_effect and civils they failed to make any provision for actually servicing the system. A valve here on the inlet or a means of directing the water away from the intake would have made my compatriots life much easier and drier. John and Robert spent most of the day wet with Robert having no less than three changes of clothes Me, well I’d opted to do the work at the turbine end Again, what was a rather difficult job could have been much simpler and quicker had the installer thought about pig removal.

 

This 280mm sponge plug was going to be inserted at the top of the 30m head penstock and be pushed or is it sucked down 300m of pipe.

  

My Mate John Macbeth of Manitoba energy would have installed a method of pig removal but this installer didn’t so I had to remove that section after the big blue valve and before the spear valve. This was actually a bit of an epic as the heavy cast iron section had been fitted with studs at one end rather than bolts so they needed removed first to see if it would actually come out without removing the elbow and spear valve. Luckily and no thanks to the installer there was a wooden beam directly above and I ‘jury rigged’ a ratchet strap to act as a lifting/lowering device.

The plan being to remove the section to check the motorised spear valve then replace it with just a few bolts so the pig could be retrieved before getting stuck in the valve or turbine.

With the water intake finally and at the expense of two cold wet compatriots finally blocked the pig is inserted into the intake and the the large blue valve opened slowly. The suction of the water being discharge down the penstock and air pressure behind the sponge pig then force it down the pipe. Well that’s the theory anyway, sadly due to poor design of the pipe and lack of communication between the two of us at the bottom with the two at the top the first attempt went ‘pear shaped’ This left the penstock empty due to an air release valve being left open and the pig stuck just far enough down the penstock so as not to able to be pulled out by hand. Of course it was made much worse by the lack of a valve to shut off the intake fully so John and Robert got soaked in the attempt to remove the pig. Not being able to communicate without walking up or down the 300m path didn’t help either but eventually we came to the conclusion that if I opened the blue gate valve fully then quickly operated the spear valve fully open then the ‘pig would fly’

  

Well, it sure did fly, rather quicker than expected to be honest and after the great ‘woosh’ came an ominous bang then bits of foam pig came out of the discharge pipe

 

We managed to retrieve them right enough but the majority was still actually embedded around the spear valve, that took quite a bit of force to remove I can tell you but the pig had done its job

The generator which had only been doing 4 or 5kW for a couple of weeks and 13kW for a couple of years was now producing 14.7kW   

So, that was it, home on the 17:30 a magnificent macaroni with nuts, cheese, olives bacon and anchovies all washed down by another pig, this time the Australian red number followed by a good night’s sleep. A rather grey but at least dry morn beckons, not to mention two pigs of my own

So, that’s it, back to the Bug

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Back under the ‘bug’ :-)

Five thirty and all is well, I tried to stay in bed longer but it was pointless, I was wide awake half an hour ago and in the end gave up, far too much to do to be stuck in bed. Not that I’ll actually be doing it just yet, gotta go over to Skye today with a mate to look at a hydro turbine. Still, it gives me time to catch up on here and ‘get all my 5h1t together’  

  

Well, as you can see, we’re home at last, caught the 16:15 ferry yesterday after a quiet enough run up from Girvan, in bed for 20:00 then awoke to the ‘peach of a day’ that was Thursday 8th of November.

Fed the animals and then it was straight out to the shed and ‘into the bug’ A big heavy parcel from Megabug https://www.megabug.co.uk/ air cooled VW specialists was sat waiting for me at Sconser on Wednesday night and I was desperate to get stuck back into the Raasay Distillery camper. Firstly cos it was blocking me shed door, secondly cos I didn’t want to forget how to put it back together and thirdly cos I’d more important projects of my own to be getting on with

 

It was getting new barrels, pistons, heads and clutch so the first thing to be done was fit all the new studs to the heads then remove the old pistons. This I made easier by warming them up first with a blow torch. The new ones would be OK as they’d been sat in the house at 20 degrees all night and if they were a little tight on the gudgeon pin I’d bung them in the oven for ten minutes.

It was whilst removing the pistons that I encountered the first minor hiccup,

  

a loose little end bush. Luckily the bush was still very much serviceable and the wear was in the conrod itself, so using the old gudgeon pin as an anvil I centre popped it all the way round and pressed it back into the rod with a G clamp. A good dose of Loctite 638 would ensure it stayed put and I’d previously marked the bush to ensure the oil galleries lined up.

 

Although the pistons are actually already installed in the barrels when they arrive I removed them anyway as there was no guarantee that they had been lubricated or that the piston rings had been staggered correctly.

 

This was a bit of a PITA as my piston ring clamp hasn’t been used in twenty years and needed much cleaning and fettling to get it to work. I had ordered another but it hadn’t arrived yet and when it does it’ll probably sit for another twenty years before it gets used I guess VW air cooled pistons are unusual in the car world in that you fit them into the barrel barrel first then slide the whole assembly over the head studs prior to pushing the gudgeon pin through the piston. Normally you would fit the piston to the con rod then push it through the liner/cylinder block whole. There is an arrow on the piston that should point to the flywheel. I had to Google that cos half the old pistons were in the wrong way round with two arrows pointing to the flywheel and two to the crankshaft pully. The gudgeon pin on most internal combustion engine is not quite in the centre of the piston being offset ever so slightly away from the ‘thrust’ side of the bore.

Piston thrusts

During the power strokes, combustion pressures force the piston downwards. However, the piston does not bear evenly against the walls of the cylinder, but is thrust against the sides of the cylinder. This is caused by the angularity of the connecting rod (Figure 6.11).
The combustion pressures force the piston downwards, and the connecting rod offers resistance, but it does this at an angle. The result is a side thrust of the piston against the cylinder wall, as shown.
The piston also has a side thrust during the compression stroke, but this is on the opposite side of the cylinder. Also, this is a lesser thrust because the downward force from compression is much less than the downward force of combustion.
The thrusts are sometimes referred to as the major and minor thrusts. Because the thrust during the power stroke (major thrust) is most important, this side of the engine is often referred to as the thrust side of the engine. It is necessary to know about the thrust side of an engine because the pistons in most engines have to be installed in a particular way. Pistons are often provided with a mark to show how they should be fitted in relation to the front of the engine.

 http://pautomotivemechanics.blogspot.com/2011/06/piston-designs.html

  

Once the barrels were on it was the turn of the heads, which on this are torqued down to a mere 18lb/ft !!! which really is not very much at all. Still, that’s what it says in the book so I guess it’s really important to make sure the threads are clean and the washers well oiled. With the heads on I set the valve clearances and much to my joy there was a huge gap in them after torqueing down the heads.

  

This had been a bit of a concern for me and I’m still at a loss as to how it came about, though I suspect the old barrels must have been too short, though that does not explain how the vehicle had actually run for so long with no valve clearance. If you look at the image on the left you can see that the rocker screw is actually within the rocker arm, the image on the far right was taken after I’d set the valve clearance and you can see the rocker screw is now where it should be.

  

As seems to be the case with these, it takes far longer to fit all the tin-ware and ancillaries than everything else and by 21:00 I’d had enough so ‘called it a day’.