PIPELINE REPAIR IN SWAMP AREAS

In June 2008 OIL&GAS JOURNAL RUSSIA published an overview of advanced pipeline repair techniques. The article gave a review of the repair methods using composite sleeve, fiberglass repair sleeve, pipeline composite reinforcing sleeve Smart Lock and Clock Spring. The article drew a response, and the team of authors received lots of questions from readers.
      The questions can be split into three groups.
      The first and mostly asked – is it possible to repair pipelines in swamp areas using Smart Lock? Yes, it is. Within the last eighteen months the scope of repairs done using Smart Lock grew by an order of magnitude. Repair works in swamp areas scheduled for winter 2008 – 2009 were 100% completed on time. Currently works scheduled for winter 2009 – 2010 are in progress; and the order package for 2010 – 2010 season is being developed.
      Another group of questions is specifically about the repair procedure using Smart Lock at low temperature conditions in swamp areas. These factors very often go together.  In such situations repair performance becomes very inconvenient: it is impossible to get to the area to be repaired in summer and it is difficult to work in winter – it’s cold.
      No Russian can be scared by cold weather, thus those repairs that are not possible to perform during a warm season are planned for winter time. But there are so many of them on the list that such parameters as repair fastness and effectiveness with its relative cheapness are coming to the fore.
      So, what difficulties go along with the pipeline repair using Smart Lock in winter at swamp areas? The answer is simple: the same as with other repair methods. Then one more reasonable question: what is the advantage of Smart Lock method?
      Here quite an obvious answer goes again. Yes, it would be more comfortable to repair a defective area replacing a pup, but it’s not always technically possible and it is rather expensive. For the value spent to replace one pup a dozen repairs using Smart Lock may be performed.
      For example, to repair a pipeline replacing a pup pipeline shall be emptied. Both in summer and winter, in dry and swamp areas this work is troublesome and expensive. A pit for the pup replacement shall be significantly large. Water shall be diverted from it throughout the whole repair process which will last at least for one work shift. Repair using Smart Lock also requires a pit but it’s much smaller in diameter than the one for the pup replacement both laterally and vertically, i.e. under the pipe. As Smart Lock installation takes no longer than two or three hours it is easier to divert water from the pit. No pipeline emptying is required. No hot works are involved. There is no need for lifting equipment as all Smart Lock parts even those used to repair 1420 mm diameter pipelines can be easily lifted by two fitters. Thanks to the above repairs using Smart Lock is much easier in terms of technical actions and arrangements, and, thus, cheaper than a pup replacement repairs. In addition Smart Lock allows repairing all metal loss types of defect including those that used to require obligatory pup replacement. Thus, the undeniable advantages of Smart Lock repair are the following:

• Pipeline repair without product pumping shutdown
• Pipeline is not required to be emptied;
• Minimum scope of earth works;
• No hot works;
• High effectiveness of materials and components used;
• High speed of repair works;
• Low cost of the repair in genera

These factors play a key role in the situation under review in this article.

Now some words specifically about the pipeline repair using Smart Lock.

Let’s review two examples. One: Repair of 273 mm diameter pipeline, swamp area in winter. Two: Urgent repair of a defect, over 0.5 m long, 377 mm diameter gas line in winter.
      Before we describe the repair procedure it should be noted that Smart Lock is not simply a sleeve, it is a whole complex including the following materials and structural parts:

• Leveling filler with epoxy grout;
• Adhesive compound (instant glue);
• Fiberglass insert;
• Clamping component including two half sleeves wound on four stainless steel pins hinged on one side using composite rings and bolted on the other side;
   

Using example one let’s review the pipeline repair procedure using Smart Lock (see picture 1).

Regardless of performance conditions the repair steps include the following (earth works excluded):

Step 1. Pipeline defective area cleaning to remove coating and corrosion traces.

      Smart Lock installation guidelines do not require pipeline cleaning to white metal, but the quality of defective area surface metal preparation impacts the repair quality.

Step 2. Bringing defects flush with pipe surface and applying the adhesive compound.

In this case repair of the pipeline wall lamination is performed, thus the defect was not required to be brought flush with the pipe surface. The critical condition for the adhesive compound application was the pipe temperature. It shall not be below 7°C. But it’s a rare case that a pumped product – and the pipeline itself – is below this temperature even in severe frosts. That’s why typically there are no issues with the process. The used adhesive compound is easily applied and it is not problematic to apply it evenly to the cleaned area to be repaired (see Picture 2).
 

Picture 2. Pipeline area prepared for Smart Lock installation

Step 3. Insert installation.

The insert is manufactured from fiberglass as strong as the pipe metal itself; it is used to build up the pipeline wall thickness at the defective area and to avoid mechanical load on welds under the sleeve.

Step 4. Assembly of the sleeve clamping component.

A clamping component consisting of two half-sleeves is installed above the insert. Its hinged structure provides for quick and easy closing of half-sleeves in a sleeve and a long bolt skirt and quality screw – for its manual fixing. Screwed connections include initial pre-tightening of bolts and final tightening of UKTM screwed connection with gauged torque as specified in the Passport for each pipeline diameter sleeves. Gauged torque is assured using a torque wrench.

Step 5.   Corrosion protection.

      Half-sleeve pins are manufactured from stainless steel. They are completely decoupled electrically from the pipeline. Smart Lock is packaged with bolts made either from stainless steel or tensile strength steel galvanized to protect from corrosion. But after the sleeve installation all Smart Lock production pockets including screwed connection pockets shall be filled anyway. Filled Smart Lock production pockets are shown on Picture 3.

Picture 3. Smart Lock with filled production pockets

      Smart Lock insert and clamping component are manufactured from corrosion resistant high-strength fiberglass and being nonconductors provide for repaired pipeline defective area water-proofing.
      In addition heat-shrinking tape reliably seals Smart Lock insert edges adjacent to existing pipeline coating.

Step 6. Markers installation.

After water-proofing of Smart Lock repaired pipeline area a magnetic marker is installed, EM marker is installed during the pit backfilling in the soil under repaired area.

Extended defects can also be repaired using Smart Lock. Picture 3 shows a repaired area of 377 mm diameter gas line where defect length was over 0.5 m along the axis.

Now let’s get back to the readers’ questions.

The third group of questions is about Smart Lock pipeline repair method training.
Specialists’ training to repair pipelines using Smart Lock is certainly a very important aspect. In this situation a general principle that “the more experience you have the higher quality and quickness are” is definitely applicable as well, but initial knowledge is necessary and is required anyway. Today for those companies willing to perform repairs using Smart Lock internally off-site trainings are arranged at their facilities but it is only a temporary solution as it becomes more and more difficult to accommodate the growing demand. At the moment the agreement is reached with the Research and Training Center KACHESTVO about joint development of the training program for the pipeline repair method using Smart Lock and about endorsement of this training program by Russian Rostekhnadzor authorities. Implementation of actions aimed at creating and approving the above training program will allow arranging scheduled training for repair personnel in the trunk pipelines industry, oil and gas recovery companies and any other companies operating pipelines including issuance of the established standard pattern certificates.