Life at the end of the road

November 10, 2018

The pig in a pipe :-)

Filed under: daily doings, hydro, pigs — Tags: , , — lifeattheendoftheroad @ 7:47 am

Woo hoo, almost 6:30 and I could have actually stayed in bed a little longer had I wanted Smile 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.

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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 Smile

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.

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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 Sad smile Me, well I’d opted to do the work at the turbine end Smile Again, what was a rather difficult job could have been much simpler and quicker had the installer thought about pig removal.

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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.

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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.

Image result for spear valve

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’ Sad smile 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’ Smile

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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 Sad smile

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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 Smile

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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 Smile Smile 

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 Smile

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So, that’s it, back to the Bug Smile

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1 Comment »

  1. That was truly fascinating … OK the plan didn’t go perfectly but the job got done and no one permanently mangled in the process. I call that a win 🙂

    Comment by Matt — November 10, 2018 @ 12:47 pm


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