Brake Pipes

[Daveg]

Wally I don't disagree with your diagram at all, the maths is using my figures and if the pipe was a perfect circle you would be exactly right, but nothing is perfect and there are different ways to work out tolerances as I have done, which I understand not everyone will follow what I have done, but one point I would like to make in all this discussions we have had is, that you have just come round to my understanding that a pipe only has one wall, where previously you were adament that a pipe had two walls, but you still insist that in your maths that you can add two wall thicknesses together and add the internal diameter to get the outside diameter, which can only every be right if and only if the circle is a PERFECT circle, otherwise your maths would be wrong.

Daveg

[wally]

Aug 22, 2012 23:03:55 GMT Daveg said:

but you still insist that in your maths that you can add two wall thicknesses together and add the internal diameter to get the outside diameter, which can only every be right if and only if the circle is a PERFECT circle, otherwise your maths would be wrong.

Daveg

My maths would still be a dam sight nearer than yours Dave!

Od-Id has to equal the wall thickness of both sides of the pipe as a diameter line goes all the way across and cuts thru the center and both sides of the pipe. The only error in my calcs is saying od-id/2 = wall thickness, as one side "may" be thicker than the other if the hole in the pipe is not central. But it still would not be as much of an error as you saying 1.49 mm wall thickness and 30% corrosion would be 0.5 mm. That is double the actual corrosion required on one side of a brake pipe to be a major safety concern and I think it is disgusting that you can actually argue the toss about this and not accept what you are being told.

I've had enough of this just as others have, so believe what you like and I hope you sleep well at nights.

Wally

[David]

Aug 22, 2012 23:03:55 GMT Daveg said:

Wally I don't disagree with your diagram at all, the maths is using my figures and if the pipe was a perfect circle you would be exactly right, but nothing is perfect and there are different ways to work out tolerances as I have done, which I understand not everyone will follow what I have done, but one point I would like to make in all this discussions we have had is, that you have just come round to my understanding that a pipe only has one wall, where previously you were adament that a pipe had two walls, but you still insist that in your maths that you can add two wall thicknesses together and add the internal diameter to get the outside diameter, which can only every be right if and only if the circle is a PERFECT circle, otherwise your maths would be wrong.

Daveg

sorry daveg but I require some form of proof to your brilliance before I acknowledge your posts in future....show us all your last PR?

[phaetonott]

Sounds right to me Wally, but a bit more confusion could be added by unnecessarily introducing pi.

It now appears that if the pipe is pitted by any more than about a quarter of a millimeter it fails.

All we need now is an approved calibrated way of measuring that 0.25mm.

Or shall we stick to the old way? use our experience, and our eyes to decide.

[Daveg]

Aug 22, 2012 23:27:22 GMT wally said:

Aug 22, 2012 23:03:55 GMT Daveg said:

but you still insist that in your maths that you can add two wall thicknesses together and add the internal diameter to get the outside diameter, which can only every be right if and only if the circle is a PERFECT circle, otherwise your maths would be wrong.

Daveg

My maths would still be a dam sight nearer than yours Dave!

Od-Id has to equal the wall thickness of both sides of the pipe as a diameter line goes all the way across and cuts thru the center and both sides of the pipe. The only error in my calcs is saying od-id/2 = wall thickness, as one side "may" be thicker than the other if the hole in the pipe is not central. But it still would not be as much of an error as you saying 1.49 mm wall thickness and 30% corrosion would be 0.5 mm. That is double the actual corrosion required on one side of a brake pipe to be a major safety concern and I think it is disgusting that you can actually argue the toss about this and not accept what you are being told.

I've had enough of this just as others have, so believe what you like and I hope you sleep well at nights.

Wally

It reads to me like there is a tone present and some misunderstanding of what I have written, maybe I can try to clarify more easily I will try.

I took a steel brake pipe manufactured by the OEM. The protective coating was removed and an OD measurement was recorded at 4.70mm

I said that I used a drill bit of 3.0mm diameter to measure the internal diameter of the pipe, which I found to be slightly greater than 3.0mm with regards slight lateral movement of the drill bit.

I said;

4.70 - 3.0 = 1.70

How did you interpret that result?

Then I said mathematically I calculated the internal diameter at 3.21mm

So;

4.70 - 3.21 = 1.49

I think I read you right when you commented here saying that I was telling everyone that the wall thickness was 1.49mm, well actually the 1.49mm refers to the annulus of the pipe in total at the extremes of the diameter, so although not correctly you could if you wished divide by 2 to get 0.745, but this is not the correct method to use as you rightly pointed out that the hole in the centre of the pipe might not be exactly central, which is why I have always said that method is incorrect.

Are you with me so far?

Now;

I have a brake pipe annulus of 1.49.

I now want to know what a 1/3 of the annulus is?

1/3 of 1.49 = 0.49

This is a third of the complete annulus all round the circumference and not at the end of the diameter as I think you all have assumed in my threads.

Now;

1.49 - 0.49 = 1.0mm

This is the minimum wall thickness, i.e the complete annulus of the pipe after the maximum deterioration allowable has occured, lets say excessive corrosion occured to the complete annulus at one point all round the circumference. Do you understand me now?

The after market pipe wall thickness measured 1.18mm before any deterioration occured, so;

1.18 - 0.25 = 0.93

Which is the stronger pipe?

OEM after excessive corrosion at 1.0mm or

after market at 0.93mm after excessive corrosion or deterioration.

Daveg

[David]

Aug 23, 2012 20:15:58 GMT Daveg said:

Aug 22, 2012 23:27:22 GMT wally said:

My maths would still be a dam sight nearer than yours Dave!

Od-Id has to equal the wall thickness of both sides of the pipe as a diameter line goes all the way across and cuts thru the center and both sides of the pipe. The only error in my calcs is saying od-id/2 = wall thickness, as one side "may" be thicker than the other if the hole in the pipe is not central. But it still would not be as much of an error as you saying 1.49 mm wall thickness and 30% corrosion would be 0.5 mm. That is double the actual corrosion required on one side of a brake pipe to be a major safety concern and I think it is disgusting that you can actually argue the toss about this and not accept what you are being told.

I've had enough of this just as others have, so believe what you like and I hope you sleep well at nights.

Wally

It reads to me like there is a tone present and some misunderstanding of what I have written, maybe I can try to clarify more easily I will try.

I took a steel brake pipe manufactured by the OEM. The protective coating was removed and an OD measurement was recorded at 4.70mm

I said that I used a drill bit of 3.0mm diameter to measure the internal diameter of the pipe, which I found to be slightly greater than 3.0mm with regards slight lateral movement of the drill bit.

I said;

4.70 - 3.0 = 1.70

How did you interpret that result?

Then I said mathematically I calculated the internal diameter at 3.21mm

So;

4.70 - 3.21 = 1.49

I think I read you right when you commented here saying that I was telling everyone that the wall thickness was 1.49mm, well actually the 1.49mm refers to the annulus of the pipe in total at the extremes of the diameter, so although not correctly you could if you wished divide by 2 to get 0.745, but this is not the correct method to use as you rightly pointed out that the hole in the centre of the pipe might not be exactly central, which is why I have always said that method is incorrect.

Are you with me so far?

Now;

I have a brake pipe annulus of 1.49.

I now want to know what a 1/3 of the annulus is?

1/3 of 1.49 = 0.49

This is a third of the complete annulus all round the circumference and not at the end of the diameter as I think you all have assumed in my threads.

Now;

1.49 - 0.49 = 1.0mm

This is the minimum wall thickness, i.e the complete annulus of the pipe after the maximum deterioration allowable has occured, lets say excessive corrosion occured to the complete annulus at one point all round the circumference. Do you understand me now?

The after market pipe wall thickness measured 1.18mm before any deterioration occured, so;

1.18 - 0.25 = 0.93

Which is the stronger pipe?

OEM after excessive corrosion at 1.0mm or

after market at 0.93mm after excessive corrosion or deterioration.

Daveg

or when it looks excessively corroded as the manual says

[nitros44]

Aug 20, 2012 8:54:31 GMT excessive said:

My initial point was that it is impossible for us to measure if a brake pipe is corroded by more than a 1/3 - We do not have that ability within the constraints of an mot test.

Yet, the manual clearly states that it has to be corroded by more than a 1/3 before we can fail it.

Think about that for a moment.

I'm the same as you guys, I go with my experience when assessing a brake pipe, but to take the manual on its wording, I do wonder how we would defend ourselves if we had to show how we measured for a 1/3rd of deterioration due to corrosion.

The answer is, we can't.

Excessive ,,,,going back to your original point

I fully agree in what you wrote,but would like to add the following which is my take on the issue of assessing brake pipes which have excessive corrosion.

My understanding on the 1/3rd issue is that it must be appreciated that to measure brake pipes is not possible,we all know that.

However there is a need for GUIDEANCE to avoid NT"s using differing standards when visually assessing brake pipes,hence a 1/3 being only a guide.

Where corrosion is present and can be seen it must be considered reasonable for us NT"s to be able to use our skill and experience to competently asses brake pipes with reasonable consistency.

At the end of the day VOSA, like and demand consistency,weather or not they get it is another debate possibly

Another Example would be in were a measurement is not possible;

Brake pads have to be worn below 1.5mm to reach the fail criteria,can we measure them!!,the 1.5mm is there for guidance only and once again its there to prevent NT"s applying differing standards its not implying to measure the component.

---

It always comes back to experience and skill if you sure beyond doubt that the corrosion has reduced the thickness of the wall then fail it/them or pass/advise,as you and others have stated

[Daveg]

I like it Nitros

Another Example would be in were a measurement is not possible;

Brake pads have to be worn below 1.5mm to reach the fail criteria,can we measure them!!,the 1.5mm is there for guidance only and once again its there to prevent NT"s applying differing standards its not implying to measure the component.

Go on Wally , give it your best shot and tell us how to measure the 1.5mm mathematically LOL ;D

If I do it for you, you will argue and try to shoot me down, so I will let you first LOL ;D, but maybe start a new thread

Daveg

[drivewasher]

FOR GODS SAKE!!! Can mods please lock this fiasco, it's getting pathetic.

If my internet provider (Virgin) wasn't blocking the other forum I'd just go there to get out of the way of this childrens party.

[Daveg]

Aug 22, 2012 23:27:22 GMT wally said:

Aug 22, 2012 23:03:55 GMT Daveg said:

but you still insist that in your maths that you can add two wall thicknesses together and add the internal diameter to get the outside diameter, which can only every be right if and only if the circle is a PERFECT circle, otherwise your maths would be wrong. Daveg

My maths would still be a dam sight nearer than yours Dave! Od-Id has to equal the wall thickness of both sides of the pipe as a diameter line goes all the way across and cuts thru the center and both sides of the pipe. The only error in my calcs is saying od-id/2 = wall thickness, as one side "may" be thicker than the other if the hole in the pipe is not central. But it still would not be as much of an error as you saying 1.49 mm wall thickness and 30% corrosion would be 0.5 mm. That is double the actual corrosion required on one side of a brake pipe to be a major safety concern and I think it is disgusting that you can actually argue the toss about this and not accept what you are being told. I've had enough of this just as others have, so believe what you like and I hope you sleep well at nights. Wally

Wally I have posted a visual representation of two pipes one being perfect and the other real world, please take the time to understand why division by 2 would be wrong by example 2 shown.

Daveg

Attachments:

[David]

Aug 25, 2012 14:54:47 GMT Daveg said:

I like it Nitros

Another Example would be in were a measurement is not possible;

Brake pads have to be worn below 1.5mm to reach the fail criteria,can we measure them!!,the 1.5mm is there for guidance only and once again its there to prevent NT"s applying differing standards its not implying to measure the component.

Go on Wally , give it your best shot and tell us how to measure the 1.5mm mathematically LOL ;D

If I do it for you, you will argue and try to shoot me down, so I will let you first LOL ;D, but maybe start a new thread

Daveg

use a standard rivet head to measure the pad IF you can see it and access it

keep it simple

[Daveg]

Aug 25, 2012 19:23:00 GMT David said:

Aug 25, 2012 14:54:47 GMT Daveg said:

I like it Nitros

Another Example would be in were a measurement is not possible;

Brake pads have to be worn below 1.5mm to reach the fail criteria,can we measure them!!,the 1.5mm is there for guidance only and once again its there to prevent NT"s applying differing standards its not implying to measure the component.

Go on Wally , give it your best shot and tell us how to measure the 1.5mm mathematically LOL ;D

If I do it for you, you will argue and try to shoot me down, so I will let you first LOL ;D, but maybe start a new thread

Daveg

use a standard rivet head to measure the pad IF you can see it and access it

keep it simple

Glad to see that you are recognised as an industry expert David ;D

Daveg

[David]

Aug 25, 2012 19:35:25 GMT Daveg said:

Aug 25, 2012 19:23:00 GMT David said:

use a standard rivet head to measure the pad IF you can see it and access it

keep it simple

Glad to see that you are recognised as an industry expert David ;D

Daveg

we don't need to use anything but a standard rivet is 1.5mm if it fits between the pad & disc P&A, basically keep it simple.......
...or do it your way and abort, go and work it out 55 times, write about it on here, argue your point get it wrong and not admit it, explain to the customer and finally test it till you meet your next problem then abort again...oh I forgot to mention ring VOSA too

Still waiting for your PR?

[David]

...and yes I am recognised as an industry expert daveg thanks for acknowledging that and making other members aware

[Daveg]

Aug 25, 2012 21:05:40 GMT David said:

Aug 25, 2012 19:35:25 GMT Daveg said:

Glad to see that you are recognised as an industry expert David ;D

Daveg

we don't need to use anything but a standard rivet is 1.5mm if it fits between the pad & disc P&A, basically keep it simple.......
...or do it your way and abort, go and work it out 55 times, write about it on here, argue your point get it wrong and not admit it, explain to the customer and finally test it till you meet your next problem then abort again...oh I forgot to mention ring VOSA too

Still waiting for your PR?

David, your talking nonesense above, first no professional would try to put a rivet between a disc face and a worn pad inside a brake caliper , secondly the abort function on Computerisation is used when a test cannot be completed because of a problem with the VTS or testing equipment or the NT.

Third in conjunction with my last diagram which shows why you are all wrong is fact, not that I am wrong, but you are the evidence speaks volumes.

Fourth I don't need to ring VOSA, but based on your replies here I think you would benefit from refresher training David.

If I were you I would probably stop worrying about PR reports becasue based on your replies I am not sure that you understand the content of their information anyway

By the way David, I am glad you understood what I meant when I said you are an expert

Daveg

[phaetonott]

FFS, now we're expected to cut the pipe to see if the hole is in the middle!?!?

Just look at it and make a decision.

I can't work out how thw scheme average test takes about 38 minutes if it takes this much working out to assess a brake pipe!

[Wesley]

Aug 25, 2012 19:04:38 GMT drivewasher said:

FOR GODS SAKE!!! Can mods please lock this fiasco, it's getting pathetic.
"
If my Internet Provider (Virgin) Wasn't blocking "The Other" Forum I'd just go there to get out of the way of this "Childrens Party".

"If", You Were As Cleverer, Cleverer, As "Them"? LOL! Then "You" Would Have The Knowledge to enable You to do This?? LOL!

Unfortunately, at this moment in time, I don`t!

[David]

Aug 25, 2012 21:50:50 GMT Daveg said:

Aug 25, 2012 21:05:40 GMT David said:

we don't need to use anything but a standard rivet is 1.5mm if it fits between the pad & disc P&A, basically keep it simple.......
...or do it your way and abort, go and work it out 55 times, write about it on here, argue your point get it wrong and not admit it, explain to the customer and finally test it till you meet your next problem then abort again...oh I forgot to mention ring VOSA too

Still waiting for your PR?

David, your talking nonesense above, first no professional would try to put a rivet between a disc face and a worn pad inside a brake caliper , secondly the abort function on Computerisation is used when a test cannot be completed because of a problem with the VTS or testing equipment or the NT.

Third in conjunction with my last diagram which shows why you are all wrong is fact, not that I am wrong, but you are the evidence speaks volumes.

Fourth I don't need to ring VOSA, but based on your replies here I think you would benefit from refresher training David.

If I were you I would probably stop worrying about PR reports becasue based on your replies I am not sure that you understand the content of their information anyway

By the way David, I am glad you understood what I meant when I said you are an expert

Daveg

All NT's\AE's & SM's are considered experts daveg, there are some exceptions and they're usually the ones who over complicate every test.

If you find it difficult (as you seem to show on this thread), to assess whether a brake pad should fail or not guage the pad thickness with a standard rivet head which is 1.5mm....take advise if your stuck daveg, especially when its FOC

[David]

oh and WTF do you post diagrams for?

use the manual like everyone else daveg and base your decisions on that and that alone, no one is interested in your opinion only the correct one from the manual. When you write the manual I'll listen gladly but until then wind your neck in a tad

[drivewasher]

Well I just looked in my rivet box and I can't see a "standard" rivet there are about 5 different dia's & 4 different lenghts. Plus they got a head on them so if you could insert one it would be at an angle because the lip/rim would foul on the disc.

David you preach keep it simple/experience etc so why do you need to use any form of gauge. I, on the other hand am a relativley new NT so I keep a simple 1.5mm allen key on the front of the lift, but I can honestley say when Iv'e looked at pads then made a decision, after a quick check with the allen key I was right. So is it really needed?