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Any idea when Crankcase relief valves became mandatory?
I'm aware of Reina del Pacifico-11 Sep 1947, described elsewhere in here, maybe the worst incident recorded of this type.
Killed 28, injured 23.
Didn't sail in it, but I saw a B&W engine in a hull built in Japan in 1985, and I'm quite certain it did NOT have crankcase relief valves.
They're easily seen, so I'm sure I didn't just miss them.
Thaks, and take care
 

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Don't know when they became mandatory but I was on a twin eight cylinder Goterverken tanker built about 1964, the relief valves exhausted upwards. I sailed on it in 1970 and it had had an explosion on one engine a couple of years before, the oiler had seen sparks when he was doing the scavenge drain pots and called the 4/E so they were both standing in the middles over the relief vave opening when it lifted, both died. After that metal screens were fitted on the side of each engine with a door you had to open to get to the scavenge drains. All the Xheads were fitted with long rods that extended out of the crankcase to a microswitch, if a Xhead bearing wore down the Xhead would touch the rod and sound the alarm.
One night as 4/E on the 12/4 watch as I approached the desk on the bottom plates between the two engines I could hear a clicking noise and saw the microswitch lever was jumping on No 6 unit Stb'd engine, I asked the 8/12 4/E what had he done and he answered nothing, it hasn't alarmed. I told him to go get the 2/E (only phone to bridge and C/E and you never phoned the C/E in those days) and I began to slow the Stb'd engine, was also concerned that the shaft generator tripped at 70 rpm, the 2/E turned up and just stopped the engine. After an hour the crankcase was opened and the Xhead white metal was sticking out the sides like soft toffee.
 

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Learned folks
Any idea when Crankcase relief valves became mandatory?
I'm aware of Reina del Pacifico-11 Sep 1947, described elsewhere in here, maybe the worst incident recorded of this type.
Killed 28, injured 23.
Didn't sail in it, but I saw a B&W engine in a hull built in Japan in 1985, and I'm quite certain it did NOT have crankcase relief valves.
They're easily seen, so I'm sure I didn't just miss them.
Thaks, and take care
Really ?!
 

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I don't know when they became mandatory. IACS unified requirements, under M9, mention first release in 1970.

The valve opening value is 0.07 Bar or 1 lb/in2! While they should be regularly tested, it is a good idea always to check them after the engine has been repainted. Epoxy paint can glue them shut! All valves that I have seen exhaust downwards, between the plates into the bilge/tank top space.

When studying, we did a little exercise for a large bore Xhead engine to see, approximately, what internal pressure would blow the door off - If memory serves, it was a little over 3 lb/in2.

Investigation has shown (as per Reina Del Mar) that if there is an explosion and the crankcase door is breached, the secondary explosion will be of a much greater magnitude.

Rgds.
Dave
 

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I am unsure of general, merchant ships and the registration, these days: However the machinery is in a registered vessel usually built to a classification requirement, and survey/inspection procedure.
However under Older Uk regulations while a passenger ship was built to classification rules, it was also subject to rules and an inspection procedure as required by Government inspectors surveyors.
One question slow speed catherdral engines may have crankcase explosions doors: I wish to beg the question of the modern high/medium speed marine diesels, either geared/electrical/hydraulically connected to the main shaft, do they have explosion doors in the crankcase?? Or is the speed and power of each crankspace, within an explosion regulation limit, according to energy that could be created under explosive conditions.
 

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Captainconfusion,
Yes, there are relief valves. There are other systems, apart from the Graviner oil mist detector, which monitor the conditions in the crankcase. These are based on oil temperature, electromagnetic discharges (dissimilar metals), etc. However, as asked by Insurers whether a cylinder/crankshaft failure was predictable on a Wartsila med. speed engine, my answer, based on calculations, was,"less than two seconds"!
Rgds.
Dave
 

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noted ! Thank you.
We had a disaster in Ellermans in the late ' 50s on the City of Bath.. A bottom end bearing bolt failed and the ensuing malee in the crankcase caused a crankcase explosion that blew the crankcase doors off - despite the crankcase relief valves. An engineer died of his injuries.
 

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I remember being told by a lecturer that some of the H&W built engines didn't have relief valves, relying on a crankcase exhaust fan, don't know how effective they were though!!
 

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Learned folks
Any idea when Crankcase relief valves became mandatory?
I'm aware of Reina del Pacifico-11 Sep 1947, described elsewhere in here, maybe the worst incident recorded of this type.
Killed 28, injured 23.
Didn't sail in it, but I saw a B&W engine in a hull built in Japan in 1985, and I'm quite certain it did NOT have crankcase relief valves.
They're easily seen, so I'm sure I didn't just miss them.
Thaks, and take care
When is a good question, as more than a few engineers were killed. I was on reefers in the 1980's and we had medium speed Pielstick engines, and they were considered high risk. Engine crankcases were fitted with Graviner oil mist detectors, which I had to set up and calibrate when we got full away on passage and changed over onto heavy oil. That was always fraught as well and more than once I peed everyone off by accidently tripping the engine as they were very fiddly and located in a precarious location. The crankcase covers had relief valves but that was I told small protection in a major incident and I was advised never stand too close to them.
 

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As a mere R/O aka Sparks - what the ~# is a crankcase relief valve?!!
Here's my understanding, subject to correction if I've got it round my neck...
It's a large spring-loaded non-return valve mounted on the side of the crankcase. Sometimes called an "explosion door." It has three main functions:
1. To let the pressure out if a hot spot, such as a piston seizure or a bearing failure, in the crankcase ignites oil vapour and causes an explosion. This prevents the pressure blowing the actual doors off.
2. To seal again once the pressure has dropped so that air can't get sucked back in to feed an even greater explosion.
3. The valve incorporates a flame trap to prevent flames getting out into the engine room.
 

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Thank you kind Sir - I am now much the wiser.
My first ship in '65 was the CITY OF PORT ELIZABETH GPLC.
It had twin Doxfords. It used to frighten the life out of me on my rare forays down into the engine room from the boat deck.
There was a walkway between the engine tops.
Those pistons going up and down, the flailing rubber hoses, noise and heat.
Had I known about the dangers of crankcase relief valves I would not have ventured further down in my quest for distilled water for the Radio Room emergency batteries!

I remain in awe and admiration for those who worked in the E/R.
 

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I joined PSNC in 1969 and heard all about the Reina. Years later as 2nd on the Hornby Grange I saw what such an explosion could do. She had suffered an explosion, been repaired, but even years later there was evidence all over the engine room. Happily no engineers were injured in this instance.
 

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Thank you kind Sir - I am now much the wiser.
My first ship in '65 was the CITY OF PORT ELIZABETH GPLC.
It had twin Doxfords. It used to frighten the life out of me on my rare forays down into the engine room from the boat deck.
There was a walkway between the engine tops.
Those pistons going up and down, the flailing rubber hoses, noise and heat.
Had I known about the dangers of crankcase relief valves I would not have ventured further down in my quest for distilled water for the Radio Room emergency batteries!

I remain in awe and admiration for those who worked in the E/R.
The "flailing" rubber hoses weren't a problem ........ until they broke, spraying hot water around :( On one ship a hose broke and wasn't spotted for a few minutes by which time the water pouring off the top platform was doing a good job of washing down the open front switchboard below(n)
 

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The "flailing" rubber hoses weren't a problem ........ until they broke, spraying hot water around :( On one ship a hose broke and wasn't spotted for a few minutes by which time the water pouring off the top platform was doing a good job of washing down the open front switchboard below(n)
A not infrequent happening, Fortunately the (ship) in question had the Switch board out of range!, but getting to the stop valve!, could get you scalded!. We had a coil of the hose rubber kept in a 40 gall drum down the shaft tunnel, the length required was marked on the E-R plates. Even in the dark and (relatively) cool the hose seemed to deteriorate quickly. Not to forget, entering the stinking hot, crankcase at sea to replace/repack the "elbow's". Whilst being coated with hot oil.!
 

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A not infrequent happening, Fortunately the (ship) in question had the Switch board out of range!, but getting to the stop valve!, could get you scalded!. We had a coil of the hose rubber kept in a 40 gall drum down the shaft tunnel, the length required was marked on the E-R plates. Even in the dark and (relatively) cool the hose seemed to deteriorate quickly. Not to forget, entering the stinking hot, crankcase at sea to replace/repack the "elbow's". Whilst being coated with hot oil.!
Ah! Those porous swinging links and elbow glands........ memories best forgotten (n)
 

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Here's my understanding, subject to correction if I've got it round my neck...
It's a large spring-loaded non-return valve mounted on the side of the crankcase. Sometimes called an "explosion door." It has three main functions:
1. To let the pressure out if a hot spot, such as a piston seizure or a bearing failure, in the crankcase ignites oil vapour and causes an explosion. This prevents the pressure blowing the actual doors off.
2. To seal again once the pressure has dropped so that air can't get sucked back in to feed an even greater explosion.
3. The valve incorporates a flame trap to prevent flames getting out into the engine room.
Very true with your comments, but two things to add from my experience with the MAN 52/55 proto types when we had many explosions from piston seizures whilst trying to modify piston skirts and rings to remove direct LO cooling from pistons
1. In one case the round explosion door opened as designed, but the large sealing O-ring was displaced out of its groove and prevented the door from re-sealing, no secondary (the big explosion) hence why I'm able to type today.
2. Given the medium speeds in container ships, in our case 3 engines are in close proximity, when the doors did explode open, LO at over 85 Deg C was a blasted on to the floor plates, jetted off the plates into the next engine, bouncing off her and up into the head room of the plates above. I was saved twice by pure luck of just being outside the blast area. On watches I used to move pretty quickly between engines.
The good old days.
 

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Getting back to the subject of crankcase explosion doors - I recall the head teacher at Sydney Tech, Len Bateman, relating that after the Reina Del Pacifico disaster, 'John Lamb was set loose in a shed somewhere attempting to reproduce crankcase explosions with the view to finding answers'. I assume that this work was undertaken for the British Internal Combustion Engine Research Association (think I've got that right?) because most relief valves had BICERA cast on them.
I don't recall reading anything about this work in Lamb's autobiography, but in his 1958 Obituary mention is made of work he did on this subject for which Institution of Mechanical Engineers awarded him the Akroyd-Stuart prize (year?). Guess that his work was put into effect soon after, but when they became mandatory - don't know.
 
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