RIL's Cryogenic Ethane Storage and Receipt Facility at Dahej tells the story of how LTHE helped its customer set a new benchmark in liquid Ethane Transportation & Storage.
When Reliance industries Limited (RIL) decided to establish the largest supply chain for Ethane from production facilities in USA to its Cracker Units in India within a short period of time, it knew that getting there wasn't going to be easy. Such a thing had never been attempted before, certainly not on the scale RIL had in mind. There were technological challenges involved in long surface transportation of liquid ethane and severe time constraints. Accomplishing the goal meant that it had to bring in the big guns – L&T Hydrocarbon Engineering (LTHE).
It was LTHE's strong execution capabilities and technological supremacy which led RIL to repose its faith in the former and award the turnkey EPC project to establish the Cryogenic Ethane Receipt and Storage Facilities at its Dahej Manufacturing Complex.
The complete Basic and Detail Engineering of the Dahej Facilities comprising Unloading Arms, 8 Km cryogenic pipeline from jetty to the plant, the Storage Tank and associated Balance of Plant (BOP) facilities, procurement and construction of double-walled full containment Cryogenic Ethane Storage Tank was awarded to LTHE in the first phase of the project in August 2014.
The project schedule posed a unique challenge. While globally, projects of this nature took anywhere from 34 to 36 months, this one was to be completed within 29 months. Further, the unloading and storage facilities including the Tank were to be designed for Dual Service of Ethane/LNG. The underground section of the cryogenic ethane unloading pipeline is one of the longest in the world which was to be designed with 'Pipe in Pipe' (PIP) technology.
LTHE partnered with M/s Saipem, world leaders in cryogenic technology for the design and engineering of the facilities.
The project team had a monumental task on hand, necessitating meticulous planning in design, procurement and construction in view of the stringent timelines.
Constructing the Ethane Storage Tank
Early commencement of Basic Engineering at Saipem, Paris and mobilisation of the project site within seven days of contract award gave a robust start to the project. Drawings for construction were released within 3 months of contract award to kick-start the RCC Bored Cast in-situ Piles (1m diameter and 38m depth). Exhaustive time motion studies were carried out to maximize the piling productivity and utilization of five Piling Rigs deployed at site within a limited area of 6000 sq. m. The efforts resulted in ensuring maximized pile output with maximum productivity up to 65 Piles per week. This resulted in completion of 536 piles within 97 days. Stringent quality checks on piles including the cross-hole sonic logging tests, dynamic load tests and pile integrity tests were implemented to make sure that the work quality didn't suffer on account of lack of time.
The concreting of the Tank Base Slab (90 metre diameter, 6500 Cum. of concrete) posed a significant challenge in ensuring a crack free slab. Thermal analysis of Base Slab was carried out utilising results of various tests done on the concrete at specialized laboratories in IIT Madras and Madrid University. A good design mix for M50 concrete was developed using GGBFS (Ground Granulated Blast Furnace Slag) to lower heat of hydration. All these efforts resulted in a crack free base slab which received all-round appreciation from the customer as well as the consultants.
The Outer Concrete wall (88.5 metre diameter) of width 800mm and height 37 metre was cast in 11 lifts using specially designed Jump Formwork. The challenge associated with casting the entire diameter of the wall lift in a single segment at heights was overcome by the use of static boom placers. With each passing wall lift, the casting time-cycle was optimised and what started off at 22 days for the initial lift was brought down to just 9 days for the latter lifts.
Significant efforts were put in by Supply Chain Management of LTHE on the global sourcing of materials of special metallurgy (9% Nickel, high strength Aluminium plates). Rigorous expediting was done to meet the stringent delivery requirements of all materials to meet the construction sequence requirements. Extensive Value engineering and design optimization helped in reduction of cutting wastages and minimization of site works substantially. 2100MT of 9% Nickel steel plates were pre-fabricated in France and transported to site.
Within 15 months from project award date, the critical construction activity of Roof Air Raising was completed creating a benchmark in Cryogenic Tank construction. The power of air was unleashed when an unsupported 810 MT roof along with the suspended deck prefabricated at grade was lifted into position at a height of 37 meters with air pressure pumped through high capacity blowers. The entire operation of air lifting was carried out by LTHE under expert supervision. Since any imbalance while air raising can have catastrophic results, each sub-activity was planned and engineered to the last detail.
Micro-scheduling, Resource planning, Access Control Plans and Quality check-lists were developed much in advance for a smooth air raising operation. Accurate COG (Centre of Gravity) calculations and appropriate counter weights ensured perfect balancing of Roof during upward movement. The outcome of all this was a smooth 16hrs continuous operation in raising the 810 MT tank roof into its position.
Inner Tank fabrication was yet another crucial activity. The inner shell construction posed significant difficulties due to its special metallurgy (9% nickel steel), limited access / confined space and working at height.
The demanding situation and need to fast-track the execution called for an innovative approach. In what was a first in the country, Phased Array Ultrasonic Testing Technique (PAUT) was implemented as NDT for the welding joints of the Inner Tank Shell, in lieu of the conventional radiography technique. PAUT has a number of technical advantages and can be carried out in parallel with other construction activities without stopping any work. Use of special welding techniques accompanied by PAUT implementation resulted in completion of inner shell fabrication in a record duration of 4 months.
The fabrication of inner tank was accompanied by a series of simultaneous construction activities inside the tank. The complete concrete wall was lined with low temperature carbon steel liner with multiple layers of bottom plates and insulation.
The tank was hydro-tested to check its integrity and the foundation settlement. It was filled up with 1, 22,000 m3 of water, the equivalent of the daily water requirement of an entire town. An elaborate arrangement of high capacity pumps ensured filling and discharge activity completion in 20 days. LTHE in line with its commitment towards water conservation ensured recycling of water back to the fire water system of RIL.
Insulation plays a vital role in meeting tank performance requirement and boil-off rate. The bottom layer of the tank and corner protection is insulated with high density foam glass and interleaving felt. Resilient Blankets are installed on the inner tank wall throughout its periphery. Plus the annular space between the inner tank and concrete wall is filled with expanded Perlite. Due to the nature of operation and dusty environment within the tank, perlite filling is considered as one of the most critical operation in tank construction. Perlite filling was completed in a continuous operation within a record time of 17 days.
Pre-commissioning activities pertaining to the Cryogenic Tank include the crucial activities of purging and drying of tank and associated pipelines. To achieve this, the tank is purged with nitrogen till the oxygen content in tank is negligible and the moisture content in the tank is completely gone.
Teamwork, meticulous planning and dedication were the hallmark of the project throughout the execution phase. The tank was mechanically completed within contractual time schedule of 29 months setting a new benchmark in execution of Cryogenic Tanks.
The highest commitment of LTHE to HSE in executing this project resulted in 'Zero LTI' and was well appreciated by the client. The project also received the highest score in the Safety Audit conducted across all RIL Projects.
Balance of Plant Facilities (BOP)
In the second phase of the project, in June 2015, RIL awarded the contract for Balance of Plant (BOP) of the ethane storage facilities to LTHE. The scope comprised 2 Km of 2 x 24" Import Pipeline and 0.8 Km 1 x 12" export line in DMD premises, Boil off Gas Compressors, Condenser, Booster Pumps, Heating System, Flare System Pipelines, Sub-Station building (83.65m x 15m x 10.7m), Control Room Building (52.74m x 24m x 6.8m) and associated facilities.
Being a fast-track project, RIL kept the deadlines very tight leading to extremely challenging contractual schedule of 19 months for Mechanical Completion. Executing a Cryogenic Balance of Plant Project with such complexities in construction and against the demanding schedule was not an easy task and required an extraordinary team effort.
Major construction volumes included:
• 18,000 Cum of RCC Works.
• 4900 MT of Structural steel
• 3 Lakh Inch Metre of Piping.
• 3500 Nos. of Cryo Supports
• 550 Km of Cabling
The completion of the state-of–the-art Sub-Station and Control Room building within 12 months was another hallmark of fast-track project execution. The Control Room has ultra-modern interiors specially designed by renowned architects.
LTHE managed to overcome the engineering challenges at the site by effective deputation of all functional lead engineers at site for field engineering support till mechanical completion.
LTHE relied on new and innovative construction methods at the site to minimize time, without compromising the design, quality and safety requirements.
The completion of BOP Construction coincided with Tank construction completion leading to pre-commissioning and commissioning of the combined facilities. Special care was taken in maintaining proper cleanliness of the systems of the pipelines and the facilities to ensure flawless start-up. The piping systems and all equipment were purged and dried with nitrogen to remove all residual moisture. Further the entire systems were cooled in phases up to temperature of -90 degree C using ethane vapor before liquid intake.
Prior to start of commissioning activities, detailed procedures were developed which helped in ensuring smooth and trouble free start-up of the operations.
The successful execution of this iconic project has set a new benchmark in execution of complex Cryogenic Storage facilities. Thanks to this remarkably challenging project and its successful execution, LTHE has now set its sights on a wider horizon in execution of such technologically challenging projects in India and abroad.