Storage Tank Accessories

Industrial storage tanks alone cannot operate safely and optimally; they require a comprehensive set of accessories, each playing a critical and indispensable role in safety, process control, maintenance, and protection of both the tank and the environment. These accessories include breathing valves, level gauges, heaters, mixers, fire suppression systems, ladders, inspection hatches, and dozens of other specialized components. The proper selection, installation, and procurement of these accessories based on stored fluid type, operating conditions, safety standards, and environmental requirements ensures flawless operation and extended tank lifespan. Below, all storage tank accessories are examined in detail.

1. Breathing & Pressure Relief Valves

These are the most critical tank accessories that prevent tank collapse or explosion due to internal pressure fluctuations:

  • Pressure/Vacuum Relief Valve (PVRV):
    • Function: Automatically opens during pressure increase (Pressure Relief) or pressure decrease (Vacuum Relief) inside the tank to prevent structural damage.
    • Application: Storage tanks for crude oil, gasoline, volatile chemicals, and fixed-roof tanks.
    • Standard: API 2000 (Venting atmospheric and low-pressure storage tanks), ISO 28300.
    • Typical Settings: Positive pressure +2 to +60 inches water column and negative pressure -0.5 to -10 inches water column.
  • Emergency Relief Vent (ERV):
    • Function: Designed for rapid pressure relief in emergency conditions such as external fire exposure (Fire Case). Has much higher discharge capacity than standard PVRV.
    • Types: Weight Loaded, Spring Loaded, and Magnetic.
    • Standard: API 2000, API 520, API 526.
  • Free Vent / Open Vent:
    • Function: Simple vent pipe without valve that provides direct connection between tank interior and atmosphere.
    • Application: Water storage tanks, non-volatile and non-hazardous fluids.
    • Note: Must be equipped with insect and bird screen.
  • Flame Arrester:
    • Function: Prevents flame propagation into the tank through vent pipes. Contains metallic mesh or plate elements that absorb heat and extinguish the flame.
    • Types: Deflagration (subsonic speed) and Detonation (supersonic speed).
    • Standard: API 2210, ISO 16852.
    • Element Material: Stainless Steel 316L, Aluminum, Monel based on gas type.
  • Pilot Operated Relief Valve:
    • Function: Features an external pilot for more precise set point control and reduced leakage (Bubble-Tight). Suitable for tanks with expensive or highly hazardous fluids.
    • Advantages: Near-zero leakage, stable operation near set point.

2. Level Measurement Instruments

Accurate monitoring of fluid level inside the tank is essential for inventory control, overfill prevention, and process management:

  • Sight Glass / Reflex Gauge:
    • Function: Direct visual display of liquid level through resistant glass. Available in Reflex and Transparent types.
    • Application: Small to medium tanks with low to medium pressure and temperature.
    • Standard: DIN 16911.
  • Magnetic Level Indicator (MLI):
    • Function: Features a magnetic float inside a chamber that moves external colored flaps. No power required, leak-free, and visible from a distance.
    • Advantages: Suitable for toxic, corrosive, and pressurized fluids.
    • Standard: API 2350.
  • Radar Level Transmitter:
    • Function: Emits microwave signals and measures return time. Available in Guided Wave Radar (GWR) and Non-Contact FMCW types.
    • Accuracy: Up to ±1 millimeter for custody transfer applications.
    • Standard: API 3.1B, OIML R85.
  • Servo Tank Gauge (STG):
    • Function: Most accurate level measurement system using servo-controlled wire and float. Simultaneously measures level, multi-point temperature, and density.
    • Application: Commercial crude oil and petroleum product tanks (Custody Transfer).
    • Standard: API 3.1B, ISO 4266.
  • Level Switch:
    • Function: Provides alarms and automatic shutdown at high-high and low-low level points to prevent overfill and pump dry-running.
    • Types: Capacitive, Vibrating (Tuning Fork), Float, Ultrasonic, and Radioactive.
    • Standard: API 2350 (Overfill protection for storage tanks).
  • Gauging Tape & Bob:
    • Function: Manual level measurement through roof manhole. Simple, inexpensive, and serves as backup method alongside automatic systems.

3. Manholes & Access Openings

  • Manhole:
    • Function: Large opening (typically 20 to 24 inches) for personnel entry into the tank for inspection, cleaning, and maintenance.
    • Types: Roof Manhole and Shell Manhole in bolted and hinged types.
    • Standard: API 650 (Welded storage tanks), API 620 (Low-pressure storage tanks).
    • Gasket: Neoprene, Viton, PTFE, or Graphite based on fluid type.
  • Handhole:
    • Function: Small opening (typically 6 to 12 inches) for limited access for visual inspection, sampling, and spot cleaning.
  • Sampling Hatch:
    • Function: Small hatch on tank roof for manual fluid sampling without opening the main manhole.

4. Heating Equipment

For maintaining fluid at desired temperature, preventing freezing, and reducing viscosity for easier pumping:

  • Steam Heating Coil:
    • Function: Spiral or U-shaped pipes at tank bottom through which hot steam flows, transferring heat to the fluid.
    • Material: Carbon Steel, Stainless Steel 304/316.
    • Application: Storage tanks for heavy crude oil, bitumen, industrial oils, wax, and fats.
  • Electric Immersion Heater:
    • Function: Electric heating elements directly immersed in the fluid. Precise temperature control with thermostat.
    • Types: Flanged and Threaded.
    • Standard: IEC 60079 (for hazardous areas), ATEX.
  • Jacket Heater:
    • Function: Thermal jacket around tank shell where heating fluid (steam or hot oil) flows in the space between jacket and shell.
    • Application: Storage tanks for resins, adhesives, chocolate, and temperature-sensitive chemicals.
  • Tank Temperature Sensor (Thermocouple & RTD):
    • Function: Multi-point temperature sensors installed at various tank heights to monitor fluid temperature profile.
    • Standard: API 2545.

5. Mixing & Agitation Equipment

  • Side-Entry Mixer:
    • Function: Mixer impeller enters fluid through tank shell near the bottom. For homogenization, preventing sedimentation, and blending additives.
    • Application: Tanks for crude oil, fuel, oil, and chemicals.
  • Top-Entry Agitator:
    • Function: Shaft and impeller enter fluid from tank roof. Suitable for process tanks and reactions.
    • Impeller Types: Turbine, Paddle, Propeller, and Anchor based on fluid viscosity.
  • Jet Mixer / Eductor:
    • Function: Uses circulation pump and jet nozzles inside the tank to circulate fluid. No moving parts inside the tank.
    • Advantages: Very low maintenance, no internal mechanical seals.

6. Nozzles & Piping Connections

  • Inlet Nozzle:
    • Function: Fluid entry point into the tank. Usually equipped with diffuser to reduce fluid velocity and prevent static electricity generation.
    • Standard: API 2003 (Protection against static electricity).
  • Outlet Nozzle:
    • Function: Fluid discharge point from the tank. Usually installed at lowest point of shell.
    • Accessories: Equipped with vortex breaker to prevent whirlpool formation and air suction into pump.
  • Drain Nozzle:
    • Function: At tank bottom for complete discharge of sediments, water, and sludge.
  • Overflow Nozzle:
    • Function: Installed at maximum allowable level and directs excess fluid to emergency tank or collection system.
  • Circulation Nozzle:
    • Function: For connecting circulation pump and mixing system.
  • Vortex Breaker:
    • Function: Cross or conical plate that prevents whirlpool formation at outlet nozzle and stops air or gas suction into pump.

7. Safety & Fire Protection Equipment

  • Foam Chamber:
    • Function: Injects fire suppression foam onto flammable fluid surface inside tank. Foam creates insulating layer, separating oxygen from fuel surface.
    • Types: Type I, II, III based on foam type and fluid.
    • Standard: NFPA 11, API 2021.
  • Foam Dam / Foam Ring:
    • Function: Metallic ring around floating roof that retains foam in the seal area.
  • Cooling Water Spray Ring:
    • Function: Water piping ring around tank shell for cooling shell during fire in adjacent tanks.
    • Standard: NFPA 15, NFPA 16.
  • Emergency Drain Valve:
    • Function: Rapid fluid discharge from tank in emergency conditions to safe containment area (Bund Wall).
  • Gas Detection System:
    • Function: Sensors for detection of flammable gases (LEL) and toxic gases (H2S, CO) around the tank.
    • Standard: IEC 60079-29, EN 50271.

8. Access & Structural Accessories

  • Ladder:
    • Types: Vertical Caged Ladder with safety cage for heights over 6 meters and Inclined Stairway for easier access.
    • Standard: API 650, OSHA 1910.27.
    • Material: Galvanized Carbon Steel, Stainless Steel, Aluminum.
  • Platform & Guard Rail:
    • Function: Safe platform around tank roof and at valve and equipment access points.
    • Standard: OSHA 1910.29, API 650.
  • Roof Platform / Rolling Ladder:
    • Function: Rolling ladder for accessing various points on floating roof of large tanks.
  • Wind Girder:
    • Function: Circular reinforcement of tank shell against wind pressure and prevention of shell buckling.
    • Standard: API 650 (Wind calculations).

9. Floating Roof Accessories

Floating roof tanks are used to reduce evaporation and volatile gas emissions and have specific accessories:

  • Floating Roof Seal:
    • Function: Seals the gap between floating roof edge and tank shell to prevent vapor escape.
    • Types: Primary Seal (Mechanical Shoe) and Secondary Seal (Wiper).
    • Material: Solvent-resistant rubber, PTFE, reinforced fabric.
    • Standard: API 650 Appendix C, EPA 40 CFR 60.
  • Pontoon:
    • Function: Hollow flotation chambers that keep the roof floating on liquid surface.
  • Roof Drain:
    • Function: Drains rainwater from floating roof to outside tank through flexible or articulated pipe.
  • Leg Support:
    • Function: Adjustable legs that hold floating roof at specified height when tank is empty.
  • Anti-Rotation Device:
    • Function: Prevents floating roof rotation around vertical axis.

10. Corrosion Protection Equipment

  • Cathodic Protection (CP):
    • Function: Prevents electrochemical corrosion of tank bottom and shell by applying electrical current.
    • Types: Sacrificial Anode (Mg, Zn, Al) and Impressed Current (ICCP).
    • Standard: NACE SP0169, API 651.
  • Sacrificial Anode:
    • Material: Magnesium (Mg) for soil, Zinc (Zn) and Aluminum (Al) for seawater.
    • Application: Installed at tank interior bottom or exterior in soil.
  • Internal & External Coating:
    • Types: Epoxy, Polyurethane, Phenolic, Glass Flake, and Rubber Lining.
    • Standard: SSPC, NACE, ISO 12944.

11. Other Important Accessories

  • Strainer & Filter:
    • Function: Removes solid particles and impurities from fluid entering or leaving tank. Available in Y-Type, Basket, and T-Type.
  • Tank Sampler:
    • Function: Samples from different fluid layers (top, middle, bottom) for quality analysis. Available in manual (Thief Sampler) and automatic (Automatic Sampler) types.
    • Standard: API 2546, ISO 3170.
  • Pressure Gauge:
    • Function: Displays internal tank pressure (for pressurized tanks). Available in analog (Bourdon Tube) and digital types.
  • Thermometer:
    • Function: Displays fluid temperature in mercury, bimetal, and digital types with thermowell.
  • Drain Valve:
    • Function: Drains water and sediments from tank bottom. Usually Ball Valve or Gate Valve type.
  • Insulation & Cladding:
    • Function: Reduces heat loss and prevents fluid freezing. Materials: Rock wool, Polyurethane foam, Cellular glass with aluminum or steel cladding.
  • Baffle Plate:
    • Function: Internal plates for reducing fluid turbulence, improving mixing, and preventing wave formation inside tank.
  • Gaskets & Seals:
    • Types: Spiral Wound, Ring Joint (RTJ), Non-Asbestos, PTFE Envelope, Rubber Sheet.
    • Standard: ASME B16.20, ASME B16.21.
  • Flange Bolting:
    • Grades: ASTM A193 B7 / A194 2H for high pressure, A325 for structural.

12. General Design & Manufacturing Standards for Tanks and Accessories

  • API 650: Welded steel storage tanks (atmospheric)
  • API 620: Large welded low-pressure storage tanks
  • API 653: Inspection, repair, alteration, and reconstruction of tanks
  • API 2000: Venting atmospheric and low-pressure storage tanks
  • API 2003: Protection against static electricity
  • API 2350: Overfill protection for storage tanks
  • API 2545: Level measurement systems
  • API 651: Cathodic protection of tanks
  • ASME Section VIII: Pressure vessels
  • NFPA 30: Flammable and combustible liquids code
  • NFPA 11: Foam systems
  • ISO 28300: Tank venting

13. Key Application Areas

  • 🛢️ Oil, Gas & Petrochemical Industries: Storage tanks for crude oil, gasoline, diesel, LPG, and petrochemical products.
  • ⚡ Power Plants: Liquid fuel tanks, boiler feed water tanks, and chemical tanks.
  • 💧 Water & Wastewater Industries: Drinking water storage tanks, chlorine tanks, and sludge tanks.
  • 🏭 Chemical & Pharmaceutical Industries: Acid, alkali, solvent, and pharmaceutical raw material tanks.
  • 🍔 Food & Beverage Industries: Oil, syrup, juice, and dairy storage tanks.
  • ⛏️ Mining Industries: Leaching tanks, slurry tanks, and acid tanks.
  • 🚢 Oil Terminals & Ports: Large storage and loading tanks.

14. Advantages of Procurement Through Specialized Trading Company

  • One-Stop Supply: Access to most comprehensive range of tank accessories from breathing valves to fire suppression systems from a single source.
  • Authenticity & Quality Assurance: Procurement from reputable global brands such as Emerson (Rosemount), Endress+Hauser, Groth, Protectoseal, Varec, Whessoe, Servomex with complete technical documentation.
  • Technical & Engineering Consulting: Assistance in proper equipment selection based on tank type, fluid, operating conditions, and standard requirements.
  • Full Compatibility: Assurance of dimensional and material compatibility of all accessories with each other and with tank shell.
  • EPC Project Support: Capability to supply complete accessory packages according to P&ID and project engineering specifications.
  • After-Sales Services: Rapid supply of spare parts, gaskets, sensors, and consumable elements.
  • Competitive Pricing & On-Time Delivery: Supply chain management for cost reduction and project acceleration.

Order Registration & Equipment Procurement Process

At Negin Javid Rasta, the order registration and industrial equipment procurement process is designed in a staged, transparent, and engineered manner so that employers and contractors can procure the equipment needed for their projects with complete confidence and in the shortest possible time.

This process is implemented with the aim of reducing technical risks, preventing equipment selection errors, and ensuring on-time delivery.

Steps for Order Registration & Equipment Procurement at Negin Javid Rasta:

1. Request Registration & Technical Specifications Submission
Receipt of procurement request along with datasheet, drawings, or required project specifications.

2. Technical Review & Specification Matching
Precise evaluation of project requirements by technical experts and proposal of best options.

3. Price & Delivery Time Announcement
Provision of transparent proforma invoice including price, procurement conditions, and delivery schedule.

4. Equipment Procurement & Quality Control
Procurement of equipment from reputable sources and conducting quality checks prior to shipment.

5. Shipment, Delivery & Support
Delivery of equipment according to schedule and provision of technical support if needed.

With this structured process, Negin Javid Rasta strives to provide a fast, reliable, and hassle-free experience for employers in the field of industrial equipment procurement.