ONGC – IMR Dept.
Training Report Pipeline Repair Methods Bhavesh Parkhe 9/10/2013
Training Report
Name: - Bhavesh Parkhe Department: - Inspection, Maintenance & Repair Objective:1. To have an in-depth knowledge of the formal functional activities of IMR [Inspection maintenance and repairs]section of Off shore Logistics in ONGC 2. To develop skills for application of theory to practical work situations. 3. To test my aptitude towards this side of career. 4. Self-evaluation and developing a strong resume for my future prospects.
Introduction 1. Scope & Objective of the Company ONGC, a national E&P company of India is one of the largest oil producers in the world. One of the major contributors is its Western Offshore Unit which comprises of number of oilfields One of the major oilfields is Mumbai High located few kms away from the western coast of Mumbai. IMR department is responsible for all the inspection, maintenance and repair work in the WOU. 2. Overview of the company’s working Oil and Natural gas is extracted from the fields by the offshore rigs and after its primary processing is dispatched to the onshore units at Uran/Hazira for further processing. Products are separated to petroleum, paraffin wax etc. 3. Details about the WOU (Western Offshore Unit) The Mumbai High field consists of number of process complexes and several unmanned jackets. Oil and gas extracted is transported between the platforms as well as onshore installations through a network of pipelines.
4. Zones of the Rig that come under IMR
The IMR department is responsible for inspection of pipeline, riser, structure of jacket below MSL, Splash zone members.
5. Contribution & functions of the IMR department Following are the basic (routine) functions:The IMR department has various functions pertaining to maintenance. BPI - Baseline Platform Inspection SZRI – Splash Zone Riser Inspection MGR – Marine Growth Removal Routine pipeline and riser repairs Inspection of PLEMs [Pipeline end modules]. Maintenance of SBMs. Pipeline Repair Techniques (leakage) Clamps Clamps are one the most economical methods of repair. They can be fixed around a leakage or a damaged part. The clamps can be temporary or permanent. There are further types featuring some variations depending on the manufacturer. The clamps can have pressure testing arrangement to check the seals. In that case dual seals can be provided. Following are some of the clamp manufacturers Oceaneering, GOV, VeeKay, Subsea Connectors Connectors are used to connect pipelines in subsea operations where hyperbaric welding can prove uneconomical. Generally, connectors are a part of sectional replacement operation. When a section of a pipe is replaced, there might be a gap in the replaced and existing pipeline which is inevitable. This gap is connected with the help of connectors. Sectional Replacement Sometimes, the region near the leakage is also found to be below the minimum requirements. In this case the whole defective pipe section must be replaced as a preventive measure. The pipe section is cut and removed. The new section is fabricated on the vessel itself, taken to the location and is connected with help of
connector. The pipeline as well as the riser can be repaired using the a bove techniques.
Details of Repair Techniques 1. Clamps Types of Clamps 1. Temporary Clamp Temporary Clamps are used when the operational pipeline needs to be repaired immediately and suitable clamp for the leakage is not available. In such cases a standard temporary clamp which is available on deck can be installed. It can be installed manually or with help of ROVs. It can be used until the permanent clamp is available.
2. Structural Clamps This type is used for permanent repair of the pipeline. It consists of steel reinforcement collets to fix the clamp. Dual seals are generally provided to perform seal verification tests. The clamps can be manually or ROV installed using stud tensioners. It also has longitudinal bolts for energising the seals.
3. ROV installed Clamps This type of equipment is used when the repair operation is hazardous to human life or not enough manpower is available. It is a relatively costlier method, hence less preferred. The movement of the clamp is controlled from deck. Guides are available on the ROV so that it is properly placed on the pipe. For tightening of bolts, remotely operated tensioners can be used.
(Based on Geometry of the clamp) 4. Patch Clamp This type of clamp can be used for minor defects. It consists of a patch of elastomeric material inside a bolted clamp.
5. Pin Hole Clamp This clamp can be used in case of small pin hole leaks. It consists of a conical seal with a pin which guides the seal on the hole.
6. Stand Off Clamp It consists of two semi-circular sleeves which can be bolted together. The inner side of the sleeve has seals to prevent leakage. These are most widely used in subsea applications. 7. Enclosure type Clamp Whenever leakage takes place at flange or any other component along the pipeline it is difficult to find immediate replacement. Thus it can be temporarily enclosed by enclosure type clamps. They cover the entire flange, hence preventing further leakage.
2. Connectors Types of Connectors 1) End Flange Connectors It is one of the cheapest way to attach a flange to a subsea pipeline where welding can prove to be uneconomical. It consists of collet grips or ball bearing grooves to hold it firmly over the pipe. Double seals can be provided for pressure verification. The flange is generally rigid. It can be swivel type depending on the situation. It gives rotational freedom to the flange so that bolt holes can be aligned.
2) Misalignment Flange connector This type of connector is used when there is lateral misalignment between the pipes to be connected. The MAF consists of a ball and socket arrangement which gives the flange rotational degree of freedom along 2 axes. By adding a swivel flange it will have all three degrees of rotational freedom. Thus, the pipes can be easily connected. 0 It provides +/- 10 Movement.
3. Sectional Replacement When the pipeline is subjected to extensive deterioration instead of localised, using repair clamps would be uneconomical. Existing flange connections can be used for removing the section of the pipe. If it does not exist the pipe must be cut at suitable section. The pipe must be replaced by another pipe of same dimensions. Welding of flanges must be done on deck.
4. Modern Non-Conventional Repair Techniques a. Epoxy filled Repair Sleeves Instead of using heavy clamps, a split sleeve can be used. The annular space can be filled with epoxy grout. This repair technique is a compromise between the conventional clamp system and composite repair system (hence also called ‘hybrid’). The epoxy can fill up all the crevices uniformly. It ensures uniform load transfer to the sleeve Hence it can be used in case of internal metal losses.
Sleeves can be welded longitudinally or clamping bolts can be provided.
b. Composite Materials Composite materials are in demand in today’s market due to their simplicity and effectiveness. They can be used for both on shore as well as in subsea applications. They are lightweight, corrosion and abrasion resistant. These solutions are developed by different companies which often do not reveal the material composition. Different companies provide different type of composite materials. Some of the common materials are plastic polymers, glass fibers, nylon fibers. The materials require corresponding adhesives.
Composite materials can be of two types i. Bandage –available on board and can be applied by staff ii. Engineered – applied by specific contractors
Composite materials can be in the
Some composite materials can be
form of wraps. Wraps are generally
directly applied over the pipe
of glass fiber. Adhesives are
section. Generally it is a mixture of
required in this repair method.
glass fibre and a resin.
Composite Material Repair Systems Clock Spring
Syntho Subsea LV (Metalyte Pipeworks)
PIPEASSURE (CSIRO)
Composite Repairs (NCA Oceaneering)
Reinforcekit (3x Engineering)
X-Protect (Composol Subsea)
Syntho Glass XT (Neptune Research Inc.)
List of Manufacturers Clamps Hydratight, Oceaneering, SubSea, QCS, ABCO subsea Connectors Vector, Oceaneering, Hydratight Hybrid and GE Energy, Clock Spring, Metalyte, Neptune Research Composite
Conclusion:These are some of the existing repair equipments in the market. The report contains a summary of the things I have learnt. All of my presented objectives were completed.
Date: 10/6/2013
Report Submitted To Mr J.S. Kalsi (Mentor) __________________
