Non-Intrusive vs Intrusive Pig Signallers - Cost

Comparative Costs (New installations and Retrofit)

New Installations

Intrusive pig signallers, by definition, require pipe penetrations.  In a new installation this results in:

1. A hole saw cut (labour and saw utilisation)
2. Purchase and installation of a threadolet or weldolet over the hole using a welding operation (Welder labour and materials)
3. Mag pent or Radiography on the weld and interpretation and certification by third party
4. Purchase of the appropriate intrusive signaller with materials of construction suitable for flow media and general environment (troublesome in hydrogen environment)
5. Proper Installation of the device to the appropriate insertion depth (trained Technician)

Field Repair and Replacements of Pre-existing Intrusive Signallers.

1. Verification by checking valves and gauging that the line is free of line pressure, isolated and free of flow media.  Ensure all seals and fittings are in good condition and that there are no emissions in the vicinity. 
2. Remove the Intrusive device from the line.  Follow the instructions and risk assessment.  Ensure these are in date and the correct revision. 
3. Processes
   1. Clean the target on the intrusive device of obstructing materials, verify proper operation and reinstall to proper depth and return line to prior status (Field Technician)
   2. Replace O rings, Clean or replace the target, verify proper operation, and reinstall to proper depth and return line to prior status (Field Technician)

Other Costs

1. Field Technicians are dispatched to “Reset the manual Flag” indicator to confirm pig passage

Non-Intrusive Pig Signallers require no line penetrations in new or pre-existing cases. They can simply be installed on or lifted from the line to change batteries or to move to another site.

Flashing local lights indicate pig passage and reset after programmed times.

Total Cost of Ownership

For New installations

TCO = Cutting + Purchasing fittings + Welding installation of the fitting + Purchase price of the Intrusive Pig Signaller + Installation costs + Maintenance costs

Preexisting Installations

Replacement

TCO = Purchase price of the Intrusive Pig Signaller + Installation costs + Maintenance costs (this chain to be added back to original TCO calculation)

Repair costs

These usually are indicated by Missed pig indications so,

TCO = “Missed pig” related costs + Purchase of repair parts + Installation costs (this chain to be added back to original TCO calculation)

Non-Intrusive

TCO = Purchase Price + Installation (strap on) + remote signal interface (if desired) and battery change out (if required)

Relative Purchase Price and considerations for where to use the appropriate Non-Intrusive technology.

Magnetic Non-Intrusive signallers are the lowest cost followed by Acoustic signallers and then Ultrasonic Active Pulse signallers.  All can achieve significant cost reductions when dealing in volume in project or blanked buy purchases.

Magnetic Signallers require the installation of magnets on or in the pig.  Acoustic or Active pulse do not require any additional costs to the pig.  Magnetics and Acoustics can be used in liquid, gas, or multiphasic applications.  Active pulse devices require liquids to operate.  Magnetics are the easiest to use with Ultrasonics a close second.  Acoustics require some knowledge of the proposed site.

As you see this is a bit more complex than considerations of environmental and safety concerns, but with the right company to assist with advice and trial units the right solution is easy.