So anyways I got a CP Question... When I clik on BigT I'm asked to login or join CP Questions, do we have to 'join' or can memebers login?

I also have a CP answer... No Todd you cannot $ave money and put five inch boompipe on a 40m pump that was engineered with 4.4. It's a weight issue and having smaller, lighter pipe is partly how a 40m can have the same structure and footprint as a thirtysix. The weight reduction isn't in the pipe its self but when its loaded. That half inch is a few 100 lbs of weight and a few 1000 lbs of leverage!

....In short. You're stuck with the small pipe Todd. And why the hell does less cost so much more in this case? Does 4.4 wear longer?    

I have 4.5 on my boom.. I think the reason it costs so much more is because its not mass produced like the 5 inch stuff . 4.5" pipe and 5" rings od fittings may be another reason.. The 4.5 wears a lot quicker then the 5" .. I had the normal steel pipes on it when the pump was new and I got 9 thousand cubes out of it !! Thats f***ing horrible! so we tried again and got the same result! Now I have esser and all is good got about 10k so far and no sign of wear but im not expecting 80k out of those pipes maybe 50 if im good to them! 

 Just think, someday the 97m will have 3" boompipe with a 48m footprint!

I'v always felt the smaller pipe wear more because the flow rate changes.Take 100 yards per hour throught the first 2-3 sections is 5" the reduce it a 1/2" it's gets more wear pressure.Probably said it wronge but still on my 1st cup,engage brain.

rule of the manufactures is 30 percent less life out of 4.4 pipe. I new alot of people that would three tip sections of pipe to one boom system.when you are out of tip section pipe 1,2,3 and deck are worn out to. this is terratorial trap rock or granite will eat up pipe fast compared to gravel

Just trying to be a bit technical in the morning here....
http://www.1728.com/flowrate.htm

Let's say you are using a Putz 16 cell (since I know those best) and your pump is on max,
wich is 160 m³/h or 31 strokes pr minute and one stroke is approx. 88 litres.

This ≈ 0.5 strokes, or 44 litrs/sec, wich is the flow rate.
This gives us a speed of 4.2882 metres/sec with a 4.5" pipe and 3.4734 metres/sec with a 5".
So the speed increases by ≈25% in 4.5" vs a 5".

What this does exactly for wear you can find out here,http://books.google.com/books?id=YoLZLJAf40cC&pg=PA130&lpg=PA130&dq=pipe+wear+vs+flow&source=bl&ots=Cl2prirJN3&sig=BO4Ws66mPMkRdpKD1FnBO7exKq4&hl=en&ei=YaCOSq7gE42L-Qb-vv3yDQ&sa=X&oi=book_result&ct=result&resnum=2
not just many having problems in the morning. :D

But if you have a quick look at one of the nomograms it looks like it doubles, but there are a lot of factors like agg. size, abrasiveness and so...

And for the weight of a 4.4 vs a 5, the weight is also 25% greater with a 5.