FREQUENTLY ASKED QUESTIONS

DECOKING

What if there is a delay during decoking, maybe a mechanical fault or a pig lodged for a period?
Our experienced pig decoking operators deal will with that and keep inspection technicians advised. The client cannot be charged by Inspection for a decoking delay, nor can it be charged by decoking for an inspection delay. The two teams works together in harmony, as colleagues.
How do you know where a pig is if it becomes lodged?
Decoking pigs are continually monitored using a pressure/flow based system.  As a pig traverses a bend, an increase in differential pressure will be observed across the pig.  This is seen as a sharp pressure spike on the on-board monitoring software.  Using a combination of pressure, flow and timings, the location of the pig is known at all times by the decoking operator.
How do you dispose of the removed coke particles?
The Cokebusters S21 pumping units contain an integrated effluent tank, which contains a two-stage filtration system.  The filters will catch any suspended solids with a particle size greater than 750µm.  Upon completion of the decoking process, the effluent tank will be emptied using a vacuum truck.

TUBE INSPECTION

Which types of metal can you inspect?
All types of furnace tube materials can be inspected, including CrMo, carbon steel, stainless steel, cast, incoloy etc.
What is the diameter size range you can inspect?
We can inspect between 2.6 and 12 inch diameter.
Can you inspect anything other than fired heaters?
Yes, we are able to inspect any process piping where a launcher/receiver can be fitted to the inlet/outlet piping.  Other common applications include HRSG boilers and pipelines.
Can you detect pinholes?
No.  The beam-spread of the ultrasound is such that pin-holes cannot be detected using this NDT method.
Can you inspect studded or finned tubes?
Yes studded or finned tubes can be inspected.
How many inspection runs do you do?
As strict company policy, we always carry out a minimum of two separate inspections with different smartpigs.  The second run is used to validate the data obtained from the first run.  More inspections runs can be carried out as required by the client.  No additional charges will be made for multiple inspections.
What if the inspection finds coke patches once decoking operators have finished?
In some respects such a finding is good news. The decision to call a pass fully clean is always one of experienced judgment. Occasionally the inspection technicians will find unremoved patches of coke contamination or inorganic material. They can precisely locate such areas for helpful advice to decoking operators, who will promptly address any problem tube(s). So, not only is the Combined Service quick & efficient, it also proves that all tubes are thoroughly cleaned.
Can you provide a Level 2 FFS Assessment?
Yes.  We are able to provide full Level 1 & 2 FFS assessments according to API 579-1/ASME FFS-1.
Can you provide a percentage growth value for creep damage?

Yes.  Creep damage is detected by looking for increases in the outside radius.  Any growth is quantified by both a dimensional and percentage value within the inspection report.

We don’t want a full inspection, but we would like you to inspect to verify that the tubes are clean. Can you supply that service?

Yes.  We can accurately detect and quantify any internal fouling using the smartpig.  This service can be provided if a full inspection is not required.

We don’t need the tubes decoking, but we want the inspection service. Is this possible?

We can provide this service, but a “sweep” clean will still be required to verify that any internal fouling/residue is removed prior to inspection.

 

How quickly can you supply a Field Report?

A Field Report is issued within 24 hours of completing the final inspection run on a particular furnace.  This is strict company policy.  Regular inspection updates will also be provided to the client throughout the inspection process.  If an anomaly is detected, the details will be provided as soon as possible.  The Final Inspection Report is issued within 7 days.

COMBINED SERVICE

So, what exactly is Combined Service?
The client refinery receives a quotation from Cokebusters offering itemised charges for decoking and inspection. In this way the client deals with just one company, receives one quotation, receives a Combined Service and is presented with one invoice.
How does this Combined Service improve timings?
As soon as decoking is completed on any process pass, inspection work can commence.  There are no shift upsets, no confusion, no missed communications and no delays.  As inspection work progresses, decoking operators remain on hand to offer the inspection team any practical assistance they might require.  They can then recommence decoking as soon as inspection data has been collected.  All personnel work together as friendly colleagues employed in the same company.
What speeds do the pigs travel?

This is dependent on the tube diameter size and the flow required for propulsion.  Typically the decoking pigs will travel between 2 – 4ms-1.  The smart pig uses a fixed data capture rate, so the speed is reduced to maximise the quantity of data obtained.  Typically the smartpig will run between 0.5 – 1.0ms-1.

Will you allow another decoking service provider to push your Smart Pig?

No. In so many ways the Combined Service is an integrated system, with interaction of our decoking and inspection activities. The Cokebusters machines are designed & built with monitoring equipment which provides constantly updating information on the position of both scraper pigs and smart-pigs. Also the machinery systems are designed so that Cokebusters operators have control of power, speed, flow and pressure – all vitally important to the safe and effective performance of an inspection.