Issue Date: April 20, 2006

Revision Date: June 27, 2011 

Ameron International

Dualoy 3000/LCX and MCX Pipe Monitoring System
Liquid Filled Pressurized Interstitial Space

CONTINUOUS INTERSTITIAL MONITORING METHOD (LIQUID FILLED)

Certification:
Certified as a continuous, liquid-filled interstitial space leak detection system for use only with Ameron Dualoy 3000/LCX and MCX fiberglass double-wall pipe.  Applicable liquids include water and aqueous solutions of brine (i.e., CaCl and NaCl) or glycols (e.g., propylene) in concentration sufficient to reduce evaporation and prevent liquid from freezing in any portion of the monitoring system under extremes of local temperature conditions.
Maximum length is 344 feet.
No restrictions on pipeline diameter.

Operating Principle:
Similar to the methodology that has been applied to liquid-filled interstitial double-walled tanks.
An applicable liquid is used to fill the pipeline interstice, which is pressurized using an air compressor or gas bottle.
High and low level pressure switches are connected to the interstitial space to ensure that pressure remains within allowable limits.
A vacuum may be placed on the interstice to assist as applicable liquid is filled from the low point in the pipeline to minimize trapped air.
The reservoir can be located in any convenient place and does not have to be at the high point of the system.
The dual-point level sensor system monitors the liquid level in the interstitial reservoir and provides an alarm if the liquid level is either too high (interstitial pressure is lost, allowing expansion of trapped vapor) or too low (loss of interstitial liquid).
The method must be used with a dual-point sensor system that will properly fit into the reservoir, is compatible with the interstitial liquid, and is on the NWGLDE list.  The spacing between the high and low sensors must be at least 10 inches.
Sensors can be used to shut down the turbine system and/or alert the operator that a potential problem exists.

Alarm Conditions:
For a leak rate of 0.10 gph out of the interstice, the maximum time to alarm for a 10-inch sensor spacing with a reservoir diameter of 3.33 inches is 3.11 hours.
This method declares a pipeline to be leaking when the loss of applicable liquid in the 3.33 inch reservoir is 0.311 gallons.
The change in level in the reservoir is proportional to the volume of fluid flowing out of the interstice.  It is cumulative and therefore not dependent on the rate of fluid loss.
Time to alarm is based on evaluations conducted using a 30% CaCl₂ (brine) solution and a leak (liquid egress) 341 feet from the reservoir.  Equivalent results are expected for other applicable liquids.
Time to alarm for a catastrophic primary pipe failure with a pressure of 38 psi is 13 seconds at a distance of 2.14 feet from the reservoir and 19.76 minutes at a distance of 341 feet. This is based on a liquid level change of 10” or 0.311 gallons in a reservoir that measures 12 inches in height and 3.33 inches in diameter.
A high level alarm indicates that the pressure in the interstice has been lost and needs to be restored. 

Applicability:

Ameron International underground double-walled piping as specified above containing gasoline, gasohol, diesel, heating oil #2, kerosene, aviation fuel, or motor oil.  Other liquids may be stored after consultation with the manufacturer.

Calibration:
Equipment requires no calibration other than an annual inspection.
The electronics must be calibrated and maintained in accordance with the sensor/monitoring equipment instructions.

Comments:
System must be designed and installed in accordance with the instructions provided by the manufacturer.
Direct burial of pipeline fittings and reservoir is permitted provided the reservoir has an observation manway at grade level.
The interstice must be filled from the low point in the pipeline to minimize trapped air.
The evaluation was conducted in an Ameron, double-wall, fiberglass pipeline with an interstitial capacity of 12.97 gallons, an inside diameter of 2.22 inches, and a length of 344 feet.
Alarm conditions are based on a fall of 10 inches of applicable liquid in a reservoir that is 3.33 inches in diameter and 12 inches in length.
Installers must be certified by both the piping and sensor manufacturer.
Evaluation was conducted with an interstitial pressure of 50 psig applied to the pipe and fittings.
Care must be taken to avoid damaging the piping by applying excessive interstitial pressure.
The third-party evaluation only addresses the method’s ability to detect leaks.  It does not test the equipment for safety hazards.     

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Equipment should be installed and operated in accordance with all applicable laws and regulations.  For full details, please refer to our expanded "DISCLAIMER" page.