Table of Contents
Introduction
Plant design and layout play a crucial role in the oil and gas industry, where safety, efficiency, and compliance with regulatory standards are paramount. One of the key standards governing plant layout is OISD-STD-118, developed by the Oil Industry Safety Directorate (OISD) in India. The OISD 118 standard is designed to provide guidelines for the safe and efficient layout of oil and gas processing plants, storage areas, and other related facilities.
In this article, we will delve into the details of OISD 118, its scope, definitions, and philosophy. We will also cover specific layouts for blocks, process units, storage tanks, LPG facilities, and utility stations, following the guidelines of the OISD-STD-118.
- Introduction
- Scope of OISD 118
- Definitions
- Plant Layout Philosophy
- Layout of Blocks/Facilities
- Layout of Process Units
- Layout of Storage Tanks
- Layout of LPG Facilities
- Layout of Utility Stations
- Separation Tables
- Importance of Compliance with OISD 118
- Resources for Further Learning
- Download OISD 118 pdf file
- Frequently Asked Questions (FAQs)
Quiz on Scope of OISD 118
1. What is the definition of a “Process Unit” as per OISD 118?
Choose the correct answer:
Explanation: A “Process Unit” is an arrangement of equipment where a specific process, such as refining or gas processing, takes place.
2. What does the term “Block” refer to in OISD 118?
Choose the correct answer:
Explanation: A “Block” refers to a designated area within the plant where one or more process units or facilities are located.
3. What is the meaning of “Safety Distance” in OISD 118?
Choose the correct answer:
Explanation: “Safety Distance” is the minimum separation distance between various facilities or equipment to minimize risk in the event of a fire or explosion.
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Scope of OISD 118
The scope of OISD 118 encompasses the safety aspects of plant design and layout for oil and gas facilities. The primary objective is to minimize the risks associated with fire, explosion, and toxic releases, while optimizing the use of space and resources. The standard applies to:
- Petroleum refineries
- Oil / Gas production and processing plants
- LPG facilities
- Pipeline installations / terminals
- Lube oil installations
- Other petroleum storage installations like crude oil gathering stations, marketing depots and terminals, and aviation storage & fueling stations
By following the guidelines outlined in OISD-STD-118, plant designers and engineers can ensure that facilities are designed to operate safely, efficiently, and in compliance with regulatory requirements.
Note: The standard does not cover green belt / buffer zones beyond the plant boundary.
Fundamental Plant Layout Philosophy
OISD-STD-118 emphasizes a structured approach to plant layout based on several key principles:
- Block Layout: Facilities should be arranged based on the general flow of raw materials through processing, storage, and dispatch.
- Separation of Blocks: Process units and dyked enclosures of storage tanks must be planned in separate blocks with roads surrounding them to act as firebreaks and for safe access.
- Traffic Management: Main traffic roads should be located outside hazardous areas, with separate approaches for employees and material movement. Truck traffic within the plant should be minimized.
- Emergency Preparedness: Each facility should have alternative firefighting access. Roads should accommodate the largest firefighting vehicles.
- Risk Mitigation: Ignition sources beyond the boundary wall must be considered. Flares, furnaces, and heaters should be oriented based on prevailing wind directions to prevent vapor drift.
Definitions
To understand the guidelines provided in OISD 118, it is important to familiarize yourself with key terms and definitions used in the standard:
- Process Unit: An arrangement of equipment where a specific process, such as refining or gas processing, takes place.
- Block: A designated area within the plant where one or more process units or facilities are located.
- Safety Distance: The minimum separation distance between various facilities or equipment to minimize risk in the event of a fire or explosion.
- Utility Station: A facility that provides essential utilities such as water, air, electricity, and steam to the process units.
Quiz on Layout Philosophy of OISD 118
1. What is the primary concern in the plant layout philosophy according to OISD 118?
Choose the correct answer:
Explanation: According to OISD 118, the primary concern in plant layout is the safety of personnel, equipment, and the environment, ensuring adequate separation distances between hazardous facilities.
2. According to OISD 118, what is necessary to maintain accessibility in plant layout?
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Explanation: OISD 118 requires that all equipment and facilities be easily accessible, which includes providing clear access paths, fire lanes, and emergency exits.
3. What does OISD 118 suggest to minimize the risk of fire, explosion, and toxic releases?
Choose the correct answer:
Explanation: OISD 118 suggests minimizing risks by strategically locating hazardous facilities away from non-hazardous ones to prevent fire, explosion, and toxic releases.
Plant Layout Philosophy
The philosophy of plant layout as per OISD 118 is based on the following principles:
- Safety: Ensuring the safety of personnel, equipment, and the environment is paramount. Adequate separation distances between hazardous facilities must be maintained to prevent the spread of fire or explosion.
- Accessibility: All equipment and facilities should be easily accessible for operation, maintenance, and emergency response. Clear access paths, fire lanes, and emergency exits should be provided.
- Flexibility: The layout should allow for future expansion or modification without disrupting ongoing operations.
- Minimizing Risk: The risk of fire, explosion, and toxic releases should be minimized by strategically locating hazardous facilities away from non-hazardous ones.
- Compliance: All aspects of the plant layout must comply with relevant national and international codes and standards, including OISD-STD-118.
Layout of Blocks/Facilities
The layout of blocks and facilities in a plant should be designed to achieve a balance between safety, operational efficiency, and cost-effectiveness. Here are some key considerations as per OISD 118:
- Process Blocks: Process units should be grouped together based on their function and hazard potential. High-hazard units should be located away from low-hazard areas and critical infrastructure.
- Control Rooms: Control rooms should be strategically placed to allow operators a clear view of the process units while maintaining a safe distance from hazardous areas.
- Storage Areas: Storage tanks for crude oil, LPG, and other hazardous materials should be located in designated storage areas with adequate safety distances from process units and other facilities.
- Utility Stations: Utility stations should be located close to the process units they serve but at a safe distance to prevent damage in the event of an incident.
Layout of Process Units
The layout of process units is a critical aspect of plant design. As per OISD 118, the following guidelines should be followed:
- Segregation of Units: Process units should be segregated based on their hazard potential. High-risk units, such as those handling flammable gases or toxic substances, should be located at a safe distance from lower-risk units.
- Safe Distance: Maintain a safe distance between process units to prevent the spread of fire or explosion. The table below provides recommended separation distances for various process units:
| Process Unit Type | Recommended Separation Distance (Meters) |
|---|---|
| Flammable Gas Processing | 60 |
| Crude Oil Distillation | 45 |
| Catalytic Cracking Unit | 50 |
| Storage Tanks | 30 |
| Utility Stations | 25 |
- Accessibility for Emergency Response: Ensure that all process units are accessible for firefighting, rescue operations, and maintenance. Designated access routes and emergency exits should be clearly marked.
- Fire and Explosion Prevention: Install fire barriers, blast walls, and other protective structures between high-hazard units to minimize the impact of a potential incident.
Layout of Storage Tanks
Storage tanks play a crucial role in oil and gas facilities. The layout of storage tanks must comply with OISD 118 to ensure safety and operational efficiency. Key considerations include:
- Separation Distances: Maintain adequate separation distances between storage tanks to prevent the spread of fire. The distance between two tanks should be at least half the diameter of the larger tank.
- Tank Farm Layout: Design the tank farm layout to allow for easy access by firefighting equipment. Tanks should be arranged in rows with sufficient space between them for maneuverability.
- Bund Walls and Dikes: Provide bund walls or dikes around storage tanks to contain any spills or leaks. The bund height should be sufficient to contain the volume of the largest tank within the bunded area.
- Ventilation and Drainage: Ensure proper ventilation and drainage in the tank farm area to prevent the accumulation of flammable vapors.
Layout of Storage Tanks: Ensuring Containment and Separation
Storage tanks require stringent layout planning:
- Must be within dyked enclosures with surrounding roads
- Capacity limits: 60,000 cum for fixed roof and 120,000 cum for floating roof tanks per dyke
- Dyke enclosure should hold full volume of the largest tank (height between 1.0 m to 2.0 m)
- Minimum separation between tanks in separate dykes: larger tank diameter or 30 m
- No process equipment inside dykes
- Tanks grouped by petroleum classification (Class A, B, C, Excluded)
- Preferably arranged in two rows; single row if >50,000 cum
- Firewalls within dykes to restrict spill hazards
- Separation distances outlined in Tables 3, 4, and 5 of the standard
Layout of LPG Facilities
The layout of LPG facilities requires special attention due to the highly flammable nature of LPG. According to OISD 118, the following guidelines should be followed:
- Storage Tanks: LPG storage tanks should be located at a safe distance from other facilities, such as process units, utility stations, and control rooms.
- Loading and Unloading Stations: Design loading and unloading stations for LPG to minimize the risk of leaks or spills. Provide spill containment measures and emergency shutdown systems.
- Fire Protection: Install fixed fire protection systems, such as sprinklers and foam monitors, around LPG facilities to quickly control any fire incidents.
- Gas Detection Systems: Equip LPG facilities with gas detection systems to quickly identify any leaks and initiate emergency response procedures.
Layout of LPG Facilities: Specific Safety Measures
LPG being highly flammable, needs specialized layout precautions:
- Vessels grouped in max six, capped at 15,000 cum each, with curb walls
- Minimum 30 m separation between different groups (spheres/bullets)
- Horizontal vessel axes must not face vital areas or control rooms
- Located downwind from process units and away from other hydrocarbons
- Spill sumps should be at least vessel diameter or 15 m away (whichever is greater)
- No shared dyke with liquid hydrocarbons
Additional guidelines for:
- Bottling plants: Safe distances, reduced trucking, downwind positioning, separate filled/empty cylinder zones
- Bulk handling: LPG truck gantries must be in separate blocks, limited loading bays, separate facilities for LPG and petroleum
- Rail loading/unloading: Restrictions on wagons and minimum distance maintained
Minimum separation distances for LPG facilities are provided in Tables 6 and 7 of OISD-STD-118.
Layout of Utility Stations
Utility stations provide essential services to the plant, such as water, electricity, steam, and air. The layout of utility stations should consider the following points as per OISD 118:
- Proximity to Process Units: Utility stations should be located close to the process units they serve, but at a safe distance to prevent damage in case of an incident.
- Accessibility: Ensure that utility stations are easily accessible for maintenance and emergency response. Provide adequate lighting, ventilation, and drainage.
- Fire Safety: Install fire protection systems, such as hydrants, extinguishers, and sprinklers, in and around utility stations.
Separation Tables
OISD 118 provides specific guidelines on the separation distances between various facilities to minimize the risk of fire, explosion, and toxic releases. The following table summarizes some of the key separation distances:
| Facility Type | Minimum Separation Distance (Meters) |
|---|---|
| Process Units | 45 |
| Storage Tanks | 30 |
| LPG Facilities | 60 |
| Utility Stations | 25 |
| Control Rooms | 50 |
By adhering to these separation distances, plant designers can create a layout that minimizes risk while ensuring operational efficiency.
Quiz on Compliance of OISD 118
1. Why is safety a key reason for compliance with OISD 118?
Choose the correct answer:
Explanation: Compliance with OISD 118 is critical for ensuring the safety of personnel, equipment, and the environment by minimizing risks associated with plant operations.
2. What does regulatory compliance with OISD 118 help to avoid?
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Explanation: Compliance with OISD 118 helps meet regulatory requirements set by the Oil Industry Safety Directorate, avoiding legal penalties and operational shutdowns.
3. How does OISD 118 contribute to emergency preparedness?
Choose the correct answer:
Explanation: Compliance with OISD 118 improves the facility’s ability to respond effectively to emergencies such as fires, explosions, or toxic releases.
Importance of Compliance with OISD 118
Compliance with OISD 118 is critical for several reasons:
- Safety: Ensures the safety of personnel, equipment, and the environment by minimizing the risks associated with plant operations.
- Regulatory Compliance: Meets the regulatory requirements set by the Oil Industry Safety Directorate, helping avoid legal penalties and operational shutdowns.
- Operational Efficiency: Optimizes the use of space and resources, reducing operational costs and enhancing productivity.
- Emergency Preparedness: Improves the facility’s ability to respond effectively to emergencies, such as fires, explosions, or toxic releases.
Resources for Further Learning
If you’re looking to deepen your understanding of piping engineering and plant layout, check out these resources:
- Complete Course on Piping Engineering
- Piping Layout Engineering
- Piping Material Engineering
- Piping Stress Analysis
- All Courses Published on EPCLAND Platform
Additionally, explore our Video Series on Comparison of Piping Items and read our Technical Articles on Piping Engineering.
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Frequently Asked Questions (FAQs)
1. What is OISD 118?
OISD 118 is a standard developed by the Oil Industry Safety Directorate (OISD) in India, providing guidelines for the safe and efficient layout of oil and gas processing plants, storage areas, and related facilities.
2. Where can I find the OISD 118 PDF?
The OISD 118 PDF can be obtained from the official OISD website or through authorized distributors. Some platforms also provide free downloads under certain conditions.
3. What are the key components of plant layout as per OISD 118?
The key components of plant layout as per OISD 118 include process units, storage tanks, LPG facilities, utility stations, and control rooms, each with specific separation distances and safety measures.
4. Why is compliance with OISD 118 important?
Compliance with OISD 118 ensures safety, regulatory compliance, operational efficiency, and preparedness for emergencies, making it critical for all oil and gas facilities.
5. How can I learn more about piping engineering and plant layout?
You can learn more by enrolling in courses such as the Complete Course on Piping Engineering or exploring other resources on the EPCLAND platform.
This comprehensive guide to plant design and layout as per OISD 118 provides essential information for engineers, designers, and professionals in the oil and gas industry. For more detailed insights and practical knowledge, explore the links provided above and join our community!
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