LINK AS 1545633 - Caterpillar

Thermal Growth Allowance
Thermal growth of exhaust piping must be planned to avoid excessive load on supporting structures. Steel exhaust pipe expands 0.0076 inches per foot of pipe for each 100°F rise of exhaust temperature (1.13 mm per meter for each 100°C). This amounts to 0.65 in (16.5 mm) expansion for each 10 ft (3.05 m) of pipe from 100° to 950°F (35° to 510°C).Exhaust Bellows Installation Limitations
If bellows-type exhaust fittings are distorted beyond limits in table while engine is operating at full throttle, service life will be greatly reduced. Flanges must be parallel.Exhaust Bellows Installation LimitationsPiping - Back Pressure
Pressure drop includes losses due to piping, muffler, and rain cap.Calculate backpressure by:P = Backpressure (psi) (kPa).psi = 0.0361 × inches water column.kPa = 6.3246 × mm water column.L = Total equivalent length of pipe (feet) (meters).Q = Exhaust gas flow (cfm) (m3/min).D = Inside diameter of pipe (inches) (mm).S = Specific weight of gas (lb/ft3) (kg/m3).To obtain equivalent length of straight pipe for each bend:Where x = 12 in. or 1000 mm.Exhaust Pipe Diameter to Meet Back Pressure Limits (English Units System)
P = Backpressure Limit (inches of water column)D = Inside diameter of pipe (inches)Q = Exhaust Gas Flow (ft3/min.) See engine performance curveL = Length of pipe (feet) Includes all of the straight pipe and the straight pipe equivalents of all elbowsS = Specific weight of gas (lb/ft3)Exhaust Pipe Diameter to Meet Back Pressure Limits (Metric Units System)
P = Backpressure Limit (kPa)D = Inside diameter of pipe (mm)Q = Exhaust gas flow (m3/min.) See engine performance curveL = Length of pipe (meters) Includes all of the straight pipe and the straight pipe equivalents of all elbowsS = Specific weight of gas (kg/m3)Smoke Measurement
Smoke Meter Conversion Chart (Sample)