Big Gus,
Your question is lacking specifics and forces me to guess what you are referring to.
"Conveying Line Pipe" = this may be referring to Powder or pellet Conveying line in a Dry product Chemical Plant.
This is the case where product (powder or pellet) is moved from one place to another by "dry", high velocity air.
The air is taken in, dried and then moved by high volume Blowers to the "Pick-up point" where the product is fed into the stream.
The piping involved is most often Aluminum of Stainless Steel. Normally piping Fittings are not used. All changes in direction and elevation are done with very long radius bends of 10'-0" or more.
Valves used in these systems include Rotary-vane pick-up valves and full port diverter valves to switch directions. Switching direction is required to switch the flow from one storage silo to another.
At the end point of a conveyor pipe there is normally a cyclone to disengage the product from the air stream. The product drops down to the bottom of the silo and exits the cyclone via another Rotary-vane valve. The air exits the top of the cyclone through a series of Bag filters to atmosphere or is recycled back to the inlet of the Blower and is reused.
Does this sound like what you might have?
prognosis: Lead or Lag