Oil and Gas Equipment Design

Understanding Oil and Gas Equipment Design in Atlantic Canada

The oil and gas industry in Atlantic Canada presents unique engineering challenges that demand specialized knowledge, innovative design approaches, and a thorough understanding of regional conditions. From the harsh offshore environments of the Scotian Shelf to onshore processing facilities throughout Nova Scotia and the Maritime provinces, equipment design must account for extreme weather conditions, rigorous safety standards, and increasingly stringent environmental regulations.

Professional engineering firms serving this sector must combine deep technical expertise with practical experience in designing equipment that performs reliably in some of the most demanding operational environments in North America. Whether developing pressure vessels for offshore platforms, designing separation equipment for natural gas processing, or engineering custom solutions for emerging hydrogen and carbon capture applications, the fundamental principles of oil and gas equipment design remain critical to project success.

Pressure Vessel Design and ASME Compliance

Pressure vessels represent one of the most critical components in oil and gas operations, serving essential functions in separation, storage, and processing applications. In Canada, these vessels must comply with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, specifically Section VIII for unfired pressure vessels, along with provincial regulations administered by authorities such as the Nova Scotia Department of Labour, Skills and Immigration.

Design Considerations for Maritime Conditions

Equipment destined for Atlantic Canadian applications must address several region-specific challenges:

• Temperature extremes: Design temperatures typically range from -40°C to +65°C, requiring careful material selection to prevent brittle fracture and ensure ductility across the full operating envelope

• Corrosive environments: Salt-laden air and marine atmospheres accelerate corrosion, necessitating appropriate material specifications and protective coatings

• Seismic considerations: While Atlantic Canada experiences lower seismic activity than western regions, equipment design must still account for appropriate seismic loading categories

• Wind and ice loading: Offshore and coastal installations must withstand significant wind loads and potential ice accumulation

Material Selection and Specifications

Selecting appropriate materials for pressure-containing components requires balancing mechanical properties, corrosion resistance, weldability, and cost considerations. Common materials for oil and gas pressure vessels include:

• Carbon steel (SA-516 Grade 70): The workhorse material for general service applications, offering good strength and weldability at moderate cost

• Low-temperature carbon steel (SA-350 LF2): Essential for applications requiring impact testing at temperatures below -29°C

• Stainless steels (304L, 316L): Required for corrosive service conditions or where product contamination must be prevented

• Duplex stainless steels (2205, 2507): Increasingly specified for offshore applications where high strength and excellent corrosion resistance are paramount

Wall thickness calculations must account for design pressure, maximum allowable stress values, corrosion allowance (typically 3-6 mm for carbon steel in corrosive service), and manufacturing tolerances. For a typical separator vessel operating at 1,500 kPa design pressure with a 1,200 mm inside diameter, wall thickness calculations following ASME Section VIII Division 1 would typically yield shell thicknesses of 12-16 mm depending on material selection and corrosion allowance requirements.

Separation Equipment Engineering

Separation equipment forms the backbone of oil and gas processing operations, enabling the efficient separation of produced fluids into their constituent phases: oil, gas, and water. Effective separator design requires careful analysis of fluid properties, flow rates, and downstream processing requirements.

Two-Phase and Three-Phase Separator Design

Separator sizing involves multiple engineering disciplines, including fluid mechanics, thermodynamics, and mechanical design. Key design parameters include:

• Retention time: Typically 2-5 minutes for oil-water separation, depending on fluid properties and required outlet specifications

• Gas velocity: Limited to prevent liquid carry-over, typically calculated using the Souders-Brown equation with K-values ranging from 0.1 to 0.35 depending on separator configuration

• Liquid settling velocity: Determined by Stokes' Law considerations, accounting for droplet size distribution and fluid viscosity

• Weir and interface level control: Critical for three-phase separators to maintain proper oil-water interface positioning

Internals Design and Optimization

Modern separator performance depends heavily on properly designed internal components:

• Inlet devices: Diverter plates, cyclonic inlets, or inlet vanes reduce momentum and promote initial phase disengagement

• Mist eliminators: Wire mesh pads or vane-type mist extractors capture entrained liquid droplets, typically achieving removal efficiency exceeding 99% for droplets larger than 10 microns

• Coalescing plates: Parallel plate packs accelerate water droplet coalescence and reduce required retention time by 40-60%

• Sand handling systems: Sand jets, jetting nozzles, and accumulator chambers address solid accumulation in produced fluids

For Atlantic Canadian offshore applications, separator design must also account for vessel motion effects, which can significantly impact separation efficiency and liquid level control stability.

Heat Transfer Equipment for Gas Processing

Natural gas processing requires extensive heat transfer equipment for applications including gas cooling, condensate stabilization, amine regeneration, and glycol dehydration. Shell-and-tube heat exchangers remain the predominant technology, though plate-and-frame and air-cooled exchangers serve important roles in specific applications.

Shell-and-Tube Exchanger Design

Heat exchanger design following Tubular Exchanger Manufacturers Association (TEMA) standards requires careful attention to:

• Thermal design: Establishing heat transfer coefficients, determining required surface area, and selecting appropriate TEMA type designation (AES, BEM, AEU, etc.)

• Mechanical design: Ensuring pressure-containing components meet ASME requirements while accommodating thermal expansion

• Tube sheet design: Calculating tube sheet thickness accounting for tube hole pattern, pressure loading, and differential thermal expansion

• Baffle configuration: Optimizing baffle spacing and cut to achieve desired shell-side velocity (typically 0.6-1.5 m/s for liquids) while limiting pressure drop

For gas processing applications common in Nova Scotia and New Brunswick, heat exchangers must handle challenging service conditions including sour gas (hydrogen sulphide), carbon dioxide, and hydrocarbon liquids. Material selection becomes particularly critical, with many applications requiring stainless steel tubes, Monel tube sheets, or exotic alloys for severe service conditions.

Air-Cooled Heat Exchangers

Air-cooled exchangers offer advantages for remote locations where cooling water is unavailable or where water treatment and disposal present environmental challenges. Design considerations specific to Maritime applications include:

• Ambient temperature range: Design for winter temperatures as low as -35°C and summer temperatures exceeding 30°C

• Wind effects: High wind conditions can reduce cooling performance; louvers and wind walls may be required

• Freeze protection: Process-side freeze protection through recirculation or auxiliary heating systems

• Corrosion protection: Hot-dip galvanizing or protective coatings for structural components exposed to marine atmospheres

Piping and Pipeline Design

Oil and gas piping systems must safely transport hydrocarbons and process fluids while meeting applicable codes and standards. In Canada, piping design typically follows ASME B31.3 (Process Piping) for facility piping and CSA Z662 (Oil and Gas Pipeline Systems) for transmission pipelines.

Process Piping Engineering

Comprehensive piping engineering encompasses several interconnected disciplines:

• Pipe sizing: Balancing capital cost against operating cost, with typical velocity limits of 20-30 m/s for gas service and 2-4 m/s for liquid service

• Flexibility analysis: Ensuring thermal expansion stresses remain within allowable limits, particularly critical for high-temperature services like amine regeneration systems

• Support design: Proper support spacing and configuration to prevent excessive pipe stress and vibration

• Material specification: Developing piping classes that define material, rating, and component requirements for each service condition

For facilities in Nova Scotia, piping systems must address the province's temperature extremes. Low-temperature considerations become particularly important for carbon steel piping, where impact testing requirements and minimum design metal temperatures must be carefully evaluated.

Valve and Specialty Equipment Selection

Proper valve selection significantly impacts system reliability and safety:

• Ball valves: Preferred for on-off service in most oil and gas applications, available in full-port and reduced-port configurations

• Gate valves: Suitable for infrequent operation where tight shutoff is required

• Globe valves: Selected for throttling applications where flow control is necessary

• Check valves: Preventing reverse flow in pump discharge and compressor systems

• Relief valves: Critical safety devices sized per API 520/521 to prevent overpressure conditions

Structural Design for Equipment Support

Equipment support structures must safely transfer loads to foundations while accommodating thermal movement, wind forces, seismic loads, and operational requirements. Structural design for oil and gas facilities in Atlantic Canada follows CSA S16 (Design of Steel Structures) and must account for regional environmental conditions.

Load Considerations

Comprehensive structural analysis must evaluate multiple load combinations:

• Dead loads: Equipment weight, piping, insulation, and fireproofing

• Live loads: Personnel access, maintenance equipment, and temporary construction loads

• Wind loads: Based on 50-year return period wind speeds, which exceed 120 km/h for coastal Nova Scotia locations

• Snow and ice loads: Ground snow loads reaching 2.5-3.5 kPa in many Maritime locations, plus potential ice accumulation on elevated equipment

• Seismic loads: Site-specific spectral acceleration values per National Building Code of Canada requirements

• Thermal loads: Restraint forces from equipment thermal expansion and piping reactions

Foundation Engineering Interface

Structural engineers must coordinate closely with geotechnical specialists to ensure equipment foundations suit local soil conditions. Atlantic Canada presents varied geotechnical challenges, from competent bedrock in some areas to soft marine clays requiring deep foundations or ground improvement in others. Equipment foundations for heavy vessels like separators and storage tanks may require driven piles, drilled shafts, or spread footings depending on site-specific geotechnical conditions.

Safety Systems and Regulatory Compliance

Oil and gas equipment design must incorporate comprehensive safety systems to protect personnel, the environment, and assets. Canadian regulations, including those administered by provincial authorities and the Canada-Nova Scotia Offshore Petroleum Board for offshore operations, establish minimum safety requirements that professional engineers must address.

Emergency Shutdown Systems

Process equipment must integrate with facility emergency shutdown (ESD) systems, typically designed to Safety Integrity Level (SIL) requirements per IEC 61511. Equipment design considerations include:

• Emergency isolation: Positioning of ESD valves to enable rapid equipment isolation

• Blowdown systems: Sizing depressurization systems to reduce equipment pressure to safe levels within specified timeframes (typically 15 minutes to reach 50% of design pressure)

• Fail-safe positioning: Ensuring control valves and automated equipment assume safe positions on loss of power or control signal

• Instrumented protection: High-level shutdowns, pressure relief, and other instrumented safeguards

Environmental Protection

Equipment design must minimize environmental impact through proper containment, emission control, and spill prevention measures. Secondary containment for storage tanks and process vessels, closed drain systems, and vapour recovery units represent common design features that demonstrate environmental responsibility while ensuring regulatory compliance.

Partner with Experienced Engineering Professionals

Successfully executing oil and gas equipment design projects requires engineering expertise, attention to detail, and thorough understanding of applicable codes, standards, and regulations. From initial concept development through detailed engineering, fabrication support, and commissioning assistance, professional engineering guidance ensures projects meet technical requirements while optimizing cost and schedule performance.

Sangster Engineering Ltd. provides comprehensive engineering services for oil and gas equipment design from our Amherst, Nova Scotia location. Our experienced team understands the unique challenges of Atlantic Canadian projects and delivers practical, code-compliant solutions tailored to client requirements. Whether you're developing new processing facilities, upgrading existing equipment, or exploring emerging energy applications, we're ready to put our expertise to work for your project.

Contact Sangster Engineering Ltd. today to discuss your oil and gas equipment design requirements and discover how our professional engineering services can support your next project.

Partner with Sangster Engineering

At Sangster Engineering Ltd. in Amherst, Nova Scotia, we bring decades of engineering experience to every project. Serving clients across Atlantic Canada and beyond.

Contact us today to discuss your engineering needs.