Notes

Slide Show

Outline

1	Acoustic temperature monitoring in gas mains Dr Mark Harper Mecon Limited, Cambridge
2	Content
3	Why test?
4	Even small leaks cost money
5	Catastrophic failures
6	Conventional Test Procedure
7	Leak test – How to Pass?
8	Polyethylene creeps
9	Temperature change…
10	Creep vs. temperature
11	Conventional pressure test for polyethylene
12	Dealing with creep and temperature
13	Acoustic temperature measurement
14	Some equations! Change in measured acoustic transit time: Linear approximation: Accuracy ~ ΔT/T₀ Proportional error due to temperature gradient ..1% error for 100°C/km
15	Acoustic measurement method Outgoing and echo pulses are windowed, fixed in time Fast fourier transforms give phase change at drive frequency Measure phase changes of order 0.1-1° (.002 -.017^c) Phase change gives velocity change, gives °C change Resolves temperature changes of 0.001 °C
16	Acoustic range
17	APT- Advanced Pressure Testing
18	Example from an operation
19	APT Usage in the UK up to June 2002
20	Large volumes! 48in MP , 370metres no useful results without temperature correction
21	Summary
22	Future Applications Check existing distribution network for leaks Improve hydrostatic testing of transmission pipework (long distances, high pressures) Leak test other liquid filled pipework, e.g. airport fuel lines filled with kerosene