Work Instruction (Used Drill Pipe Coating) - NOV

USED DRILL PIPE

INTERNAL PLASTIC COATING CLASSIFICATIONS

EFFECTIVE DATE

08/09/10

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WORK INSTRUCTION

This coating evaluation procedure is an uncontrolled document from NOV Tuboscope and may be used without permission.

Copyright NOV Tuboscope. 2009. All Rights Reserved.

SCOPE: To provide a general guideline for evaluating the condition of internal plastic

coatings in used drill pipe. RECOMMENDATIONS:

1. Pipe to be visually inspected shall be cleaned internally, preferably with high pressure water jetting equipment. Removal of drilling mud, chemical residues, dust and dirt, and other visible contaminants is required. Debris generated from the water blast step should be visually inspected to see if any coating became disbonded during the process.

NOTE: Water Blast should not exceed 15,000psi pressure. Recommend

use of a commercially available 360 nozzle. Do not use a pencil point nozzle.

2. The pipe I.D. is dried with compressed air to remove residual water prior to

visual inspection. 3. To help determine fitness for purpose, Classes 1, 2, 3, and 4 have been

established to provide guidelines for evaluating the condition of the coating.

4. Several tools will be needed to perform the coating inspection:

a. High intensity light (alternatively, a mirror can be used to capture the sunlight if the evaluation is taking place outside and there is a sufficient amount of sun)

b. A hinged mirror capable of extending into the ID of the pipe for a visual evaluation of the internal upset run-out

c. A knife to be used to test the adhesion around areas of damaged coating

5. Photographs showing the varying conditions of the Classifications are

recommended for training inspectors and can be used to assist in decisions. The classifications are broken down further by three areas of concern within the drill pipe: (1) the tool joint, (2) the upset run-out, and (3) the tube body. The effects of corrosion are more severe in the upset run-out area as well as the tube body. The tube body is the part of the pipe that has the thinnest steel and will therefore see a corrosion pit or body wall loss failure first. The upset run-out, while having areas of thicker steel than the tube body, is the area that

USED DRILL PIPE


EFFECTIVE DATE

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WORK INSTRUCTION



sees much higher stress due to the several changes in geometry. A pit in the upset run-out is a starting point of a stress crack which can then lead to a wash-out. For these reasons, more concern is taken with minimal coating damage in these areas.

6. Coating loss in the tool joint, up to 100%, is not always in and of itself sufficient reason for down grade. However, if coating loss in tool joint is creeping into the run out area, this area needs to be thoroughly evaluated for coating adhesion as outlined in this guide.

7. The benefits of a comprehensive used drill pipe coating inspection program

are to ultimately extend the useful life of the pipe and prevent premature failures caused by pitting type corrosion in the critical transition area (weld line and internal upset area).

PICTORIAL DESCRIPTION OF DEFECTS

Figure 1: Blistered Coating

USED DRILL PIPE


EFFECTIVE DATE

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WORK INSTRUCTION



Figure 2: Coating Delaminating (Peeling) away from an area of damage

Figure 3: Wireline Cuts in Coating

USED DRILL PIPE


EFFECTIVE DATE

08/09/10

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WORK INSTRUCTION



CLASSIFICATIONS:

CLASS 1 (Premium) STATUS: Re-use

For the ID coating to achieve a class 1 (premium) designation it can contain:

Description:

o Minor abrasion and scrapes down the tube and in the critical transition area. The metal substrate cannot be exposed in any of the areas of abrasion.

o No corrosion products (rust or scale) are present in the tube or transition area.

o I.D. Coating is not blistering or delaminating (peeling off).

Figure 4: Class 1 (Premium) in the Tool Joint

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Figure 5: Class 1 (Premium) in the Upset Run-out

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EFFECTIVE DATE

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Figure 6: Class 1 (Premium) in the Tube Body.

Figure 7: Internal camera view of Class 1 coating in the tube body

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CLASS 2 STATUS: Re-use

Description:

Wireline and tool damage to the coating in the tooljoints is normal and acceptable to a 25% loss of coating film. Using a knife, test the adhesion of the coating around the area of damage to ensure that significant coating undercreep is not present. If undercreep is present, take measures to remove loosely adhered coating

The I.D. coating in the tube body and the upset run-out contains limited wire line cuts and tool damage.

Presence of surface corrosion (rust) is visible, but no significant pitting is present. In addition, there should be no serious underfilm (undercreep) corrosion present. This can be determined by using a knife to pry at the coating around the area of damage. Coating removed from this area that has evidence of rust attached to the underside of the coating is evidence of underfilm corrosion. If underfilm corrosion is present, this joint will be downgraded to a minimum of Class 3.

Overall there can be coating loss of 5% or less in the tube body (with no more than 3% being confined to one area). In the upset run-out, limited cuts and scrapes can be present, but there is minimal coating loss in this area (less than 2%). In the areas of coating loss, there should be no evidence of corrosion pitting taking place. If need be use a Boroscope to more closely evaluate coating condition in the tube body.

Even though there are areas of mechanical damage down to the metal substrate, the coating shows no signs of blistering or delaminating (peeling off). As with the determination of underfilm corrosion, coating delamination can be determined by obvious peeling of the coating around areas of damage or by the use of a knife to check adhesion around the area of damage. Coating that is easily removed constitutes delamination.

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EFFECTIVE DATE

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WORK INSTRUCTION



Figure 8: Class 2 Coating in the Tool Joint

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EFFECTIVE DATE

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Figure 9: Damage caused during the re-hardbanding of used drill pipe can lead to coating degradation, but in the tool

joint, coating loss is less of a concern

USED DRILL PIPE


EFFECTIVE DATE

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Figure 10: Class 2 Internal Up-set Run-out. Note the damage in the tool joint coating bleeding into the upset-runout.

Figure 11: Class 2 Tube Body. Note pinhole areas of coating damage and minor indication of rust on the left.

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EFFECTIVE DATE

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CLASS 3 STATUS: Re-use/Re-coat

Description:

The I.D. coating in the tube body contains wireline cuts and tool damage.

Underfilm corrosion is present but physical removal is not severe and only exposes a minimal amount of steel.

Coating loss is 15% or less in the tube body (with no more than 8% confined to one area of the pipe).

Damage to the transition area (upset run-out) is observed but coating loss is less than 15% and the onset of pitting type corrosion has not yet occurred.

I.D. coating is not blistering or delaminating (peeling off). Coating that is blistered or showing signs of delamination will automatically downgraded to Class 4.

Damage to the coating in the tooljoints is normal and coating loss of up to 60% is acceptable. Ensure that coating showing signs of delamination are added to the lost coating to generate an accurate percentage of coating damage.

NOTE: Re-use of this pipe in normal drilling operations is acceptable. However, the

coating should be re-inspected after each well drilled or completed. NOTE: Re-coating of this class pipe should be considered in deep, high temperature, high

pressure wells (especially directional wells) with significant amounts of CO2 and/or H2S, or for use in workover/completion operations.

NOTE: Water Blast can be used to dislodge any coating that may have been loosened due

to long term exposure to the environment.

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EFFECTIVE DATE

08/09/10

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WORK INSTRUCTION



Figure 12: Class 3 Tool Joint. Note that the coating has been breached in several areas, but there is no peeling.

Figure 13: Class 3 - Damage to the upset run-out viewed with a hinged mirror

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EFFECTIVE DATE

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Figure 14: Class 3 Tube Body. Note the several areas of coating loss down to bare steel, there is no peeling of the coating in those areas.

CLASS 4 STATUS: Re-coat

Description:

Moderate to severe coating damage in the tube body and transition area with severe underfilm corrosion observed during the adhesion testing at areas of coating damage.

Coating loss in the tube body is 16% or more with the onset of pitting corrosion.

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EFFECTIVE DATE

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Coating loss in the transition area is 16% or more with the onset of pitting corrosion.

I.D. coating shows evidence of blistering and delamination (peeling). Up to complete tool joint coating loss.

NOTE: 100% loss of coating in the tool joint is not an immediate rejection. Further evaluation of the upset runout and tube body should be the final determining factor on the rejection of a joint.

Figure 15: Class 4 Tool Joint. Note the extensive loss of internal coating and the presence of pitting corrosion

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Figure 16: The presence of blisters indicates coating degradation which can be caused by excessive temperature,

chemical exposure, and/or the coating reaching the end of its useful life

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EFFECTIVE DATE

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Figure 17: Class 4 Internal Upset Run-out. Note the extensive loss of coating, the presence of underfilm corrosion

and the presence of pitting corrosion.

Figure 18: Coating damage in the tool joint that propagates from the tool joint, through the upset run-out and into the

tube body leading to a Class 4 rating

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Figure 19: Class 4 Tube Body. Note the peeling of the coating around the areas of damage and the blistering

beginning to form.

Figure 20: Delamination of the coating in the tube body automatically drops the joint to a Class 4

UCLASS 1 (Premium) STATUS: Re-useUCLASS 2 STATUS: Re-useUCLASS 3 STATUS: Re-use/Re-coatUCLASS 4 STATUS: Re-coat

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Work Instruction (Used Drill Pipe Coating) - NOV