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workover tubing/ risers
19 February 2021
Dear colleagues,
What could be the practice and standards to make sure workover tubing/ risers are good to rerun??
(As I know API5CT applies only for new manufactured OCTG)
Thanks for your insights
3 answer(s)
Augusto
Consultant [retired Shell staff]
SPREAD Associates
Total Posts: 284
Join Date: 02/09/05
In my experiece, to reuse safely tubing connections you should use 

the 1983 AMF TKC coupling > API ($ =2API=2/3 VAM). It can be considered semi premium technology because they use thicker couplings - the "J" slot  does not exist - but have no metal to metal seal.This thicker centre of the AMF couplings avoid the stresses of one box interfering with the other, therefore enabling frequent reuse.

In a way the AMF Tuboscope concept was followed by the real Premium Couplings  & metal-to-metal seal technology

Punch
Managing director Punch Energy Services
Punch Energy Services
Total Posts: 21
Join Date: 24/06/20
Hello Florent,

Ideally the operator shall have a good picture of the condition of the tubing in the Well prior the workover. By logging the tubing string they shall have a good feel on wall thickness loss or pitting.



Having a good view on the condition prior starting a workover will not put you with your back against the wall.
When it is known prior the job that (a part) of the string shall be replaced, there is time purchasing material, rather than being on the well and finding out you cannot re-run half of the string.

After pulling and laying down the joints can be cleaned in inspected. API 5A5 is for new pipe but can provide guidance as well as API RP 5B1.

In addition, the operator shall also state what is acceptable (e.g. w.r.t. wall thickness loss), they are aware what functional spec is required and shall set minimum material requirement to meet.

As you work for Vallourec, please check with VAM Field Service and/or VAM Services. Expect they can also provide some guidance, on the other hand it may be hard to set a standard if you are used to new products.
If you do not know whom to contact, check with Mr Francois David at VAM Services (if he is still around) and/ or Mr. Alastair Brodie.

With regards to riser, you can perhaps touch base with 2H Offshore and/or Claxton engineering, they are familiar with inspections, maintenance and repair of risers. Also DNV have written down a recommended practice concerning this.


Best regards,

Marcel de Klerk

Dan
Workover Engineer
SPREAD Associates
Total Posts: 23
Join Date: 01/08/18

Dear Holl,

Any tubing string which stayed in the well shall be inspected and tested for reuse purpose.  

Check for NORM requirements.

Follow the appropriate handling procedure (API and OIM procedure).

Example:

- Slip elevators are recommended for running special or bevelled/ splay couplings

- It is recommended to place the backing-off / unscrewing tongs close to the coupling.

- Hammering the coupling to break the joint is an injurious practice When tapping is required use the flat face, and tap lightly at the middle and completely around the coupling.

- Disengage all of the thread before lifting the tubing out of the coupling.

- Threads are protected against dirt or injury when the tubing is out of the well.

- The tubing placed in the derrick will be properly supported to prevent undue bending.

- The tubing with the external diameter of 60 mm and larger should be pulled in stands.

- Distribute joint and tubing wear by moving a length from the top of the string to the bottom each time the tubing is pulled.

- Before loading or unloading make sure that the thread protectors are tightly in place.

- Load tubing with all couplings on the same end of the truck.

- When unloading by hand, use rope slings to control the tubing.

- When rolling tubing on the rack, keep tubing parallel and do not allow tubing to gather momentum or to strike the ends.

- Handling the tubing on racks only, with a minimum height of 0.5m above the ground, and only with thread protectors appropriately fitted.

- For proposes of safety, ease of inspection and handling, tubing should not be stacked higher than 10 feet (3 m).

- Provide wooden strips as separators between successive layers of tubing so that no weight rest on the couplings (minimum three spacing strips).

- Only elevators in good condition with equally long elevator links with complete latch assembly should be used.

 

When tubing is being retrieved because of a tubing failure, it is imperative for future prevention of such failures that a thorough metallurgical study be made.

Perform tubular cleaning.

Perform Ultrasonic Wall Thickness measurement, Borescope, FLUT inspections following API RP 5A5 / API 5CT.

Identify pitting along the body of the tubulars, both external and internal.

Define the pitting depth and identify solution to erase the pitting or to confirm qualification/rejection.

Check Pin and Box metal loss, pitting, galling, or any other defects/damages

Classification after tubing inspection, wall thickness based:

Onshore

White: Tubing with less than 35% wear – can be reused in wells.

Blue: Tubing with a wear between 36 to 55% - can be reused in wells with small depths till 1,000 m.

Red: Tubing with wear more than 56% - not to be used in wells and must be discarded.

Offshore

White: Tubing with less than 15% wear – can be reused in wells.

Blue: Tubing with a wear between 16 to 35% - can be reused in wells with shallow depths up to 1,500 m.

Red: Tubing with wear more than 36% - not to be used in wells and must be discarded.

As for the riser, normally at least once per year inspection shall be carried out either the riser was in service or not.

I hope my answer is helpful for you.

Dan

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