How to Repair Pipe Leaks Without Hot Works

Pipe corrosion happens regularly and complete wall loss of pipe or through-gap imperfections are a general event at numerous places.

In the Oil & Gas and Offshore industry where combustible gasses are available, it is important to alter these sorts of pipe leaks and pipe imperfections with cold curing repair. This is due to the fact that hot works are by and large precluded.

Composite repair framework utilizing composite wrap must meet the base prerequisites and perform at the normal level under compelling conditions. Various composite repair materials are accessible on the open market today, however there are few that have the testing and capacity to perform at the raised temperatures which may be experienced.

Gathering Pipeline Data & Information

At the point of performing online pipe leak repairs, it is important to follow in agreement to ASME PCC2 and ISO 24817 guidelines and necessities. All information for the pipeline working pressure, temperature, pipe size and pipe medium ought to be accumulated and analysed.

Point by point Engineering Calculation and Application Method of Statement

A point by point engineering calculation and report particularly targeted towards the pipe leak must be created to decide the amount and kind of materials to be utilized. The strategy for application itemizing an orderly repair method might be given and endorsed by the customer.

Site study ought to be led before work initiation, so all dangers are evaluated and analysed into danger evaluation report. All Personnel Protective Equipment ought to be worn and danger alleviating/ decreasing steps utilized to minimize or stay away from every single superfluous danger.

Surface Preparation of Affected Pipe Section

Before work begins, consistently attempt to stop or lessen the pipeline pressure and temperature to the maximum ability. Beginning surface readiness by utilizing the grit blasting technique – sanitise affected pipe surface to SA 2.5 standard at when possible. At areas where grit blasting is impractical, these areas should be sanitised with proper non-spark apparatuses. The length of surface planning ought to be in agreement to the Engineering Calculation Report given. While performing surface planning, pipe surface ought to stay dry throughout the procedure. Set up the pipe surface roughness to about 60 to 80 microns. Utilize a surface roughness analyzer to affirm the arranged surface roughness has been accomplished.

Initiation of Pipe Leak Repair Works

Initiation of pipe repair technique – pipe leak repair procedure ought to start within 4 hours after the surface arrangement has been finished. Prior of starting of pipe repair works, make sure the leak area is appropriately checked. 

Use the latex gloves and manipulate enough quantity of SS106 Seal Stic underwater epoxy stick to cover the range of the leak. Put the blended Seal Stic onto a stainless steel sheet metal. Then, set up a few packs of SealXpert stainless steel clip by cutting a fitting length of the steel clip. Join the cut-off length of stainless steel clip with movable fasteners. Wrap the connection with movable fastener with a PVC tape. Put the stainless steel backing against the SealXpert stainless steel clip while the Seal Stic faces the pipe surface, away from the leak area. Tighten the movable fastener of SealXpert stainless steel clip a little and slide the few sets of clip to the leak area. These SealXpert stainless steel clips ought to be situated by one another, securing both the center and edge of leak area.  Keep on tightenning the movable fastener of SealXpert stainless steel clip while guaranteeing that the Seal Stic is protecting the leak opening.

Remaking of Affected Pipe Section

When the leak is captured, use SealXpert PS102 metal repair putty. Blend the hardener part of PS102 metal repair putty into the resin bowl and use the blended repair putty over the arranged pipe area. The thickness of the coat ought to be in agreement to the Engineering Calculation Report given. Permit the covered SealXpert PS102 repair putties to cure for enough time and look out for the condition of the leak. Utilize a barcol hardness analyzer to affirm the cured putty has acquired at least 85 Shore D hardness. 

 

Composite Pipe Wrapping

Use the latex gloves and open the Wrap Seal PLUS fiberglass repair tape and submerge it in water for 10 seconds; crush the roll while submerging it in water. Take off the fiberglass tape from the water and begin wrapping the Wrap Seal PLUS^TM fiberglass repair tape. The wrapping of fiberglass tape ought to begin no less than 100mm to 200mm preceding the leak region. Wrap the pipe as hard and equitably as could be expected under the circumstances, pulling marginally after each round of wrapping. Use the whole roll over the pipe surface with no less than 50% overlap for the whole pipe repair length. All length of wrapping ought to be in agreement to Engineering Calculation Report. Repeat the wrapping for a particular number of layers of Wrap Seal Plus fiberglass repair tape and lastly tapering off with about 25mm over every wrapping layer. The wrapping ought to be done in one direction.

Examination of Repair

Permit the repaired zone to be cured for a few hours (length of time is reliant on pipeline working condition). Analyse to affirm the last Barcol hardness estimation.

Repair work is finished and the repaired framework can be worked back to typical working condition.

Surface Preparation for an Effective Pipe Leak Repair

One of the single most important aspect in achieving successful pipe leak repair using pipe repair kit is the surface preparation of the affected pipe section to be repaired. For repairs to carbon steel pipe it is normally possible to achieve durable adhesion strength through means of mechanical abrasion being the only method of surface preparation. It is important that the nature of the abrasion technique is fully specified in accordance to standards e.g. blast cleaned to Swedish Standard SA3.

Different Grades of Rust 

Surface Contaminants

Residues of oil, grease, marking inks, cutting oils etc. after fabrication operations will seriously affect the adhesion of applied coatings and must be removed. It is erroneous to think that subsequent cleaning operations will remove such contaminants and it is bad practice to permit them to remain on the surface. Failure to remove these contaminants before blast cleaning results in them being distributed over the steel surface and contaminating the abrasive. Suitable organic solvents, emulsion degreasing agents or equivalents should be applied to remove contaminants in preparation for subsequent descaling treatments. Further guidance can be obtained from BS 7773 ‘Code of Practice for Cleaning and Preparation of Metal Surfaces

Surface Preparation Methods

Surface preparation can be performed via abrasive blast cleaning or by power and hand tools.

By far the most significant and important method used for the thorough cleaning of mill-scaled and rusted surfaces is abrasive blast cleaning. This method involves mechanical cleaning by the continuous impact of abrasive particles at high velocities on to the steel surface either in a jet stream of compressed air or by centrifugal impellers. The latter method requires large stationary equipment fitted with radial bladed wheels onto which the abrasive is fed. As the wheels revolve at high speed, the abrasive is thrown onto the steel surface, the force of impact being determined by the size of the wheels and their radial velocity. Modern facilities of this type use several wheels, typically 4 to 8, configured to treat all the surfaces of the steel being cleaned. The abrasives are recycled with separator screens to remove fine particles. This process can be 100% efficient in the removal of mill

scale and rust.

When applying abrasive blast cleaning, the standard grades of cleanliness for are:

Sa1      Light blast cleaning.

Sa2      Thorough blast cleaning.

Sa2.5   Very thorough blast cleaning.

Sa 3     Blast cleaning to visually clean steel

Surface cleaning by hand tools such as scrapers and wire brushes is relatively ineffective in removing mill scale or adherent rust. Power tools offer a slight improvement over manual methods and these methods can be approximately 30% to 50% effective but are not usually utilised for new steel work fabrications.

Hand Tool cleaning (St Grade)

•      Removes mill scale, rust etc., from steel

•      Cleaned using hand wire brushing, sanding, scrapping and chipping

•      Mostly used when power tool cannot be used

•      Feasible for localised/ small jobs

•      St 2-B, C or D grades are typically employed

Power Tool Cleaning (St Grade)

·         Removes loosely adhering mill scale & rust

·         Does not remove tightly adhering mill scale & rust

·         Rotary wire brushes , sanding disc and needle guns are the tools employed

·         Relevant prep grades are St2-B, C or D and St3-B, C or D

Blast Cleaning

·         Removes mill scale, rust etc., from steel

·         Abrasive jet of particles in a compresses air stream impinges on the surface for cleaning

·         Imparts a surface roughness to the steel

·         Widely used method for complete surface preparation in the repair industry

·         Sa 1, Sa 2, 2.5 or Sa 3 are typically employed

Once the pipe surface has been prepared to the required standards and the surface profile has met the required roughness, subsequently the repair works should commenced within 4 hours.