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Successful CDU/VDU Project Execution during MRPL PHASE III Expansion
Mangalore Refinery and Petrochemicals Limited (MRPL), a subsidiary of Oil and Natural Gas Corporation Limited (ONGC) operates a petroleum refinery at Mangalore, Karnataka. The Refinery has two existing Crude Distillation units with downstream Hydro-crackers and other refinery units.

MRPL's Phase III expansion plans primarily focus on Upgradation of low value products to high value products, increase in capacity to 15 MMTPA by addition of a new 3.0 MMTPA crude unit, to process cheaper crudes (Sour/Heavy and High TAN), production of petrochemical feed stocks, viz Propylene, Maximise distillate yield, upgrading entire HSD into BS III/IV grade.

CDU/VDU Unit and Facilities
The unit broadly consists of crude pre-heating section, two stage desalting, post heating section for heat recovery, crude heater, crude distillation column, crude column overhead system, crude column product withdrawal, and cooling system, vacuum distillation column, vacuum column overhead system, ejector system, vacuum column product withdrawal, and cooling system, Naphtha stabiliser column to recover fuel gas and LPG, Naphtha splitter column, product caustic wash, and water wash system wherever required, LPG Amine treating unit, LPG Mercaptan removal unit, and Kerosene treating unit.

The following products meeting various specifications leave the unit battery limit Fuel gas, LPG, Light Naphtha, Middle range Naphtha, Heavy Naphtha, Kerosene, Diesel, Heavy Diesel, Vacuum Gas Oil and Short Residue. The unit consists of the following main processing facilities sections:

1) Feed Treatment Facilities
• Electric Desalter: 3.0 MMTPA. Distilation Facilities
• A tmospheric Distillation Unit - to match 3.0 MMTPA crude distillation capacity.
i. Pre-flash Drum: 3.0 MMTPA.
ii. Crude Column/Stabiliser/Naphtha Splitter.
• Vacuum Distillation Unit: To match 3.0 MMTPA crude distillation capacity.

2) Product Treatment Facilities
• LPG Amine Section: To match 3.0 MMTPA crude distillation capacity.
• L ight Naphtha Caustic wash: To match 3.0 MMTPA crude distillation capacity.
• M edium Naphtha Caustic wash: To match 3.0 MMTPA crude distillation capacity.
• H eavy Naphtha Caustic wash: To match 3.0 MMTPA crude distillation capacity.

CDU/VDU Unit - Process MRPL Phase III CDU/VDU unit is designed to handle range of API crudes. Essentially, unit is designed for BH - AH type of crudes. The unit has been designed to meet challenges associated not only with variation in crude fractions but also processing high acidic TAN (Total Acid Number) crude.

The unit has also aims for providing extensive heat recovery system around the crude preheat trains - leading to more number of heat recovering equipment in the unit.

The processing of wide variation of crude led to designing the system with extensive flexibility with provision of bypassing facility across most of the heat exchanger in case of any leakages.

Metallurgy selected for this unit is exotic (SS 316L with restriction on minimum concentration of Molybdenum) and proper selection of piping as well as equipment MOC has proved to be a challenge. This also resulted in challenges to procurement strategy and sourcing the exotic materials in quick time.

In a single plot area (ISBL)- assimilation of two technology suppliers  packages have been taken care (EIL and UOP). The new Crude and Vacuum Distillation Unit (Unit No. 310 /311) of MRPL Ph-III Refinery Project is designed to process 3.0 MMTPA of Arab Heavy (AH) and Mumbai High (MH) Crude.

CDU/VDU Unit - Project Highlights - Key Project Statistics

CDU/VDU Unit - Project Highlights - Safety
• Safety track record at CDU/VDU has been ver y good and appreciated by MRPL.
• 9.5 million Man-hours put in at CDU/VDU site by contractors and Jacobs staff.
• Commissioning of CDU/VDU done in very safe and incident free manner.
• More than 300 training programmes covering 5000 workmen and staff done in addition to special campaigns like 'Hand safety' and 'Electrical safety'.

1) Safety Training Metrics

2) Safety Monitoring Metrics

3) Safety Performance Report

Overall Costing - Individual Head

Value Plus Suggestions
1) Value Plus No. 01 - Shifting of Analyser to safe area: Process Stack Analyser for Fired Heater is located in safe area and is provided with split AC without any pressurisation as per the norms. Tender specification required pressurisation system for Analyser Shelter even though located in Safe Area. However, Pressurisation is not required if Analyser shelter located in safe area. We have suggested the same to client and they have agreed to this suggestion. - Value Plus savings - 25 lakhs.

2) Value Plus No. 02 - Moving Satellite Rack Room (SRR) closer to the sub-station: Initially SRR room was located outside CDU/VDU phase III plant area. It was located at east side of CDU/ VDU plant area. As per this location estimated cable length required between substation (MCC) and SRR is estimated around 370 metre per run. It was suggested to change the location of SRR inside the CDU/VDU plant area and close to sub-station This change of location resulted in saving of cable length around 320 metre per run. Value Plus savings - 26 lakhs.

3) Value Plus No. 03 - Pile Reinforcement:
Design of pile reinforcement was submitted by contractor for the load case 'Tension with bending' was considering the equivalent area of inscribed square in 500mm dia pile. This was done on account of non-availability of design charts (for circular section for Tension with bending case) in SP-16. This approach was too conservative. The main bars derived accordingly in each pile as '9 nos - 20 dia' Jacobs suggested a more economic design based Limit State Design concepts considering full diameter and that the same are in use in the industry. Design was revised to main bars in each pile as '4 x 20 mm dia + 4 x 16 mm dia'. Reinforcement bar requirement was reduced by 130 tons which gave an Value Plus Savings of about 55.00 lakhs

4) Value plus No. 04 - Evaluation & Inclusion of additional vendors to project vendor list for (a) Machine Monitoring System and (b) Desalter packages: Tender was issued to vendors initially for (a) Supply and installing of machine monitoring system and (b) supply of Desalter package as per project vendor list. Offers received against both enquiries were significantly high. Additional vendors therefore were evaluated and included to the vendor list. Tenders were re-issued on a competitive basis to all including the additional vendors. - Value Plus savings - 950. 00 lakhs.

Mid-course Corrections
1) Statutory compliance: Initially LP steam drum and the Exchanger were ordered on different vendors. However approving statutory authorities considered this to be a complete package and informed that LP Steam Drum and Exchanger along with the associated piping risers and down-comers need to be construed as one system/package. Thus approval needs to be sought from the approving statutory authorities by only one manufacturing agency. Therefore LP steam drum order was cancelled and re-ordered on the Exchanger vendor to comply with the statutory requirement without jeopardising on the overall delivery schedule.

2) Additional small bore contractor introduced: Total quantum of small bore piping was nearly 60,000 inch meters (nearly 15 per cent of total piping work). Also delay in supply of pumps and instruments affected timely release of fronts for small bore piping associated with these. This led to a bunching effect as small bore piping fronts associated with instruments and pumps got quickly released in short span of time. Considering the large quantum and sequence of work a separate contractor exclusively for small bore piping was introduced.

3) Augmentation for instrument and electrical installation work: Difficulty of instrument and electrical contractors to mobilise resources, materials, necessitated a) additional manpower supply contract (b) direct purchase of materials in his scope, (c) additional supervision from PMC and (d) more resource deployment from client for loop checks etc. Therefore material like instrument tubes, valves, fittings, hoses etc. could be made available to the instrument contractor in good time and the lack of manpower from the contractors end did not impact the schedule adversely.

4) Delay in inputs for engineering: During licensor selection for ATF, necessitated a prolonged discussion with the potential licensors with respect to finalising terms and conditions, requirements etc, which resulted in considerable delay in selecting the package. This resulted in civil contractor waiting for fronts. This was overcome by assumptions; lay out decisions, elevation of equipment being adjusted with skirt length changes etc.

5) Mechanical erection contract: Major order of mechanical erection and piping contract had to be re-tendered for due to some bidders quoting who had failed in the past and had potential to derail the project schedule. To make up for the lost time due to re-tendering, temporary facilities like paved area for spool fabrication, construction power facilities were kept ready prior to contractor s mobilisation to site.

6) Hiring of DG sets: To expedite the precommissioning of the unit sufficient capacity DG sets were hired and installed in the project site. This helped in plant lighting thereby increasing the output of construction during night, start and expedite the precommissioning activities of motors, SRR and substation.

Actions Taken to Provide Smooth Work Fronts at Site
1) Pump foundations:
There are about 150 pumps in the plant and most of them below the pipe rack and adjacent to the column grids of the pipe rack. It was decided that engineering should be completed with all pipe rack and pump foundations in the same foundation network, leaving only the frame details at top on hold till pump details were available. This helped in completing the underground works without waiting for vendor finalisation/inputs for pumps.

2) CDU/VDU columns and associated critical activities: Supply, erection and subsequent works around the columns dictate the completion of the project. This is due to the requirement of hold on structure/foundation in the vicinity of columns for the erection of columns. The central stair tower, ejector structure and equipment there-in, equipment foundations, underground pipe lines, cable trenches were all coming up in the hard stand area (viz lifting trajectory) of the erection crane. About 400 MT of structural work, 50000 in mtr of piping in the vicinity of all piping including large bore Cladded pipes) were coming up in this area.

Construction time was saved considerably by adopting the following engineering/ construction approach rather than the conventional approach:
• Complete all the foundationand underground piping work in the area in advance.
• Elevate the hard stand level for the crane by about one meter above the foundation.
• Level of structure, to provide adequate cushion.
• Modularise the structure for ejector and central stair tower so that erection and site welding time was substantially reduced. For this splice joints were specially designed, keeping in view the capacity of crane, Appurtenances of the columns like platforms, large dia pipes were attached along with the equipment prior to erection.
• The heavy duty crane, which was brought in specifically for the column lift was retained to complete the lift-up of all large dia pipes and heavy pieces before dismantling the boom.

3) Piping and mechanical erection work: Piping material front and contractor resources - As in any ISBL unit in a refinery, the piping works at site was the single most important activity that decided the overall completion schedule. The CDU/ VDU unit has about 4, 00,000 in mtr of piping. The overall line count was about 4,500 lines. Significantly, there was a substantial amount of small bore piping (roughly about 60,000 in mtr). This can be gauged from the fact that a total quantity of 115 km of pipe was consumed for the 4, 00,000 in mtr piping.

4) Heat Exchanger Building: The heat exchanger building which houses most of the heat exchangers is a 90 X 15 metre building and with two floors. The construction sequence and schedule was indicating that the roof slab of the building was getting completed after the arrival of many exchangers which are to be located below the roof slab.

5) Maximising Construction Output during monsoon: The average rainfall during the monsoon periods in this region is more than 4000 mm. It was decided in consultation with client to provide a safe working environment so that following activities could be carried out during monsoon unhindered.

• Piping Works: - Of the total piping, 32 per cent of pipes are to be laid on pipe rack.
• Fire Proofing: - Steel structures to be fire proofed.
• Cable Trench: - Cable-trench activity at grade below pipe rack to be taken up.
• Pipe Trench: - Underground pipe trench at grade below pipe rack to be taken up.
• Pump Foundations: - Pump foundations below pipe rack to be taken up.

Considering the above work a proposal was put up to cover the pipe rack with tubular structure and G.I sheets. Similarly all the trenches and underground pipes completed were connected together and rainwater collected and discharged to the outside. As planned above works could be achieved which otherwise could have affected schedule. Cost incurred in covering the pipe-rack was small as compared to benefits by way of (a) work fronts released and (b) work output achieved. This decision has helped the project as it can be seen from the rain fall statistics of Monsoon 2010 which started from last week of May 2010 and extended up to 15th of December 2010 and had witnessed nearly 5000 mm of rain in the period.

Details of works executed with above arrangement during monsoon from 15th May 2010 up to 15th December 2010.