Rectangular Pressed Steel Tanks –

IS 804 - Scope Key Specifications & Tables

IS 804 covers design and dimensions of rectangular tanks with external flanges. Key data includes:

1. Typical Sizes & Weights (Clause 6.2, Table 4)

2. Tanks 5m Deep, Plate Thickness 5, 6, 8 mm (Clause 5.0)

3. Tanks 2.5m Deep, Plate Thickness 5 & 6 mm (Clause 2.50)

IS 804: Key Definitions & Specifications

Clause 2.0 Definitions:

• Cold Water or Liquid: Water/liquid with temperature ≤ 40°C.

Plate Thickness (Clause 6.3, Table 5)

Tank Dimensions & Capacities (Examples)

Notes:

• Thickness varies by tank depth and plate location.
• Dimensions and weights increase with tank size.
• Use these tables for preliminary design and selection.

flowchart TD
    A[Tank Depth] --> B{Plate Location

IS 804: Key Specifications & Types of Pressed Steel Tanks

Types of Pressed Steel Tanks (Clause 3.1)

• Type 1: All flanges external
• Type 2: All flanges internal
• Type 3: Bottom flanges internal, side flanges external

(Refer Fig. 1 in IS 804 for flange locations)

Dimensions & Thickness (Clause 6.2 & 3.15)

• Depths available: 1.25 m, 2.50 m, 3.75 m, 5.00 m
• Sheet thickness: 3.15 mm (uniform for all tanks)
• Type 1 tanks: Open tops, sizes, weights, and capacities detailed in Tables 1-4 of IS 804

Typical Parameters for Type 1 Tanks (Example from tables)

Advantages (Clause 0.2)

• Ease of erection & dismantling
• Standardized construction
• Facilitates transport & re-erection

flowchart LR
    A[Pressed Steel Tanks] --> B[Type 1: All flanges external]
    A --> C[Type 2: All flanges internal]
    A --> D[Type 3: Bottom internal, Side external]

For detailed dimensions and weights, consult Tables 1-4 in IS 804.

IS 804 - Materials: Key Specifications for Tank Plates

1. Minimum Plate Thickness (Clause 6.3, Table 5)

• Note: For hot liquids with specific gravity ≤ 1.0, minimum thickness is 6.0 mm (Clause 6.3.1).

2. Material Specifications

• Structural steel as per IS 226 (Third Revision, 1975)
• Hot rolled carbon steel sheet and strip as per IS 513 (Third Revision, 1973)
• Fasteners: Black hexagonal bolts and nuts as per relevant IS standards
• Welding electrodes as per IS 814 (Parts I & II) - 1974

3. Typical Tank Sizes & Capacities (Examples from Clause 2.50 and 5.0)

IS 804: Components and Jointing Materials – Key Points

1. Jointing Material (Clause 5.3)

• Must be insoluble in the stored liquid.
• Should withstand temperature variations of the liquid (see Clause 1.2).
• Type depends on tank use; selection agreed between purchaser and manufacturer.
• Ensures leak-tightness and durability.

2. Sheet Thickness (Clause 3.15)

• Uniform thickness of 3.15 mm for tank sheets.

3. Capacity Considerations

• Tanks with joints as per Fig. 2 have a slight reduction in capacity due to joint volume.
• This reduction is proportionate and should be accounted for in design.

Typical Specifications Summary (from Table 2 and Clauses)

Practical Notes:

• Choose jointing material compatible chemically and thermally.
• Account for capacity loss in design calculations.
• Use external flanges as per Table 2 for standard sizes and weights.

flowchart LR
    A[Stored Liquid] --> B[Tank Sheet (3.15 mm)]
    B --> C[Jointing Material]
    C --> D[Insoluble & Temp Resistant]
    D --> E[Ensures Leak-tightness]
    E --> F[Capacity Slightly Reduced]

This ensures safe, durable tanks with predictable capacity.

IS 804: Dimensions & Plate Thickness for Steel Tanks

1. Minimum Plate Thickness (Clause 6.3, Table 5)

2. Typical Tank Dimensions & Plate Numbers (Select Depths)

3. Notes on Plate Thickness & Dimensions

• Bottom plates are always thicker due to higher hydrostatic pressure.
• Side plates thickness varies by tier; lower tiers thicker than top

IS 804: Fabrication and Welding Key Points

Welding (Clause 7.7)

• Welding by metal arc process per IS 816-1956.
• Plates and connections must be clean, smooth edges, pads in full contact.
• Welds made down hand position.
• Weld size as per Figs. 5 to 9 (e.g., pad welds, socket welds).
• Welds must be even, crack-free, fully fused, no undercut or blow holes.

Fabrication (Clause 7.1)

• Plates heated uniformly and formed in press or pressed cold with V-die flanges.
• Flanges pressed square or at 45°.
• Bolt holes drilled/punched accurately; spacing ≤ 80 mm.
• Bolt diameters:
  • For 1.25 m³ tanks: 12 mm (roof up to 10 mm or 8 mm with ≤ 55 mm spacing).
  • Other tanks: 14 mm or more (roof up to 12 mm).
• Washers recommended under nuts.

Plate Thickness (Clause 6.3, Table 5)

Welding Joint Types (Fig. 5 to 9 Summary)

• Fig. 5: Tapped socket/boss welded to tank plate.
• Fig. 6: Screwed flange welded to tank plate.
• Fig. 7: Single pad welded.
• Fig. 8: Double pad welded (for 50 mm pipe).
• **Fig.

IS 804: Erection and Installation Key Points

1. Erection Guidelines (Clause 8.1 & 8.2)

• Tanks must be erected as per manufacturer’s detailed drawings and instructions.
• For tanks with external flanges at ground level, ensure adequate working space all around, underneath, and above the tank for safe erection.

2. Minimum Plate Thickness (Clause 6.3, Table 5)

3. Support & Access (Clause 1.25, Fig. 10 & 11)

• Provide rolled steel joist supports with a minimum clearance of 0.65 m for access during erection and maintenance.
• Alternatively, dwarf wall supports may be used for pressed steel tanks.

flowchart TD
    A[Start Erection] --> B[Check Manufacturer Drawings]
    B --> C[Prepare Site & Supports]
    C --> D[Ensure 0.65m Access Clearance]
    D --> E[Assemble Plates per Thickness Table]
    E --> F[Allow Working Space Around Tank]
    F --> G[Complete Installation]

Summary: Follow drawings, maintain plate thickness as per depth, provide proper supports & access, and ensure working space for safe erection and maintenance.

IS 804 - Testing: Key Specifications & Tables

1. Minimum Nominal Thickness of Plates (Clause 6.3, Table 5)

2. Typical Tank Sizes, Weights & Capacities

• Clause 6.2 & 2.50m depth tanks (Table 4):

• Clause 5.0 (5m depth tanks):

IS 804: Marking and Identification Key Points

1. Marking Requirements (Clause 12.1)

• Attach a nameplate prominently showing:
  • Manufacturer's name
  • Capacity
  • Dimensions
  • Other purchaser-required details
• Use indelible identification marks for easy erection and site fabrication.

2. Standard Mark (Clause 12.1.1)

• The Standard Mark certifies compliance with IS 804 under BIS supervision.
• Its use is governed by the Bureau of Indian Standards Act, 1986.
• Indicates quality control and continuous conformity checks by BIS.
• License for use of the Standard Mark must be obtained from BIS.

3. Information to Supply with Enquiry/Order (Appendix A)

• Specify:
  • Type of tank (Type 1, 2, or 3)
  • Type, number, and position of manholes and covers

4. Approximate Empty Weight Table (for tanks of various nominal sizes)

IS 804 - Purchaser and Manufacturer Agreement: Key Points

1. Plate Thickness (Clause 6.3.2)

• For liquids with specific gravity > 1.0 (cold/hot), plate thickness shall be mutually agreed between purchaser and manufacturer.

2. Material Marking (Clause 12.1.1)

• Material may bear the BIS Standard Mark, ensuring compliance with BIS inspection, testing, and quality control.

3. Information to be Supplied by Purchaser (Appendix A, Clause 0.5)

Purchaser must provide:

4. Inspection & Quality Control (Clause 10.1 & 11.1)

• Purchaser or rep. has right to inspect and reject non-conforming materials.
• Components must be packed securely to prevent damage during transit.

Summary Diagram of Agreement Flow

flowchart TD
    A[Purchaser] -->|Provide detailed info| B[Manufacturer]
    B -->|Manufacture as per IS 804| C[Inspection by Purchaser]
    C -->|Approve or Reject| B
    B -->|Deliver packed components| A

Note: Thickness and other technical parameters for specific liquids must be jointly decided; refer to IS 804 Appendix A for detailed purchaser info requirements.

IS 804: Name Plate and Identification (Clause 12.1)

• Name Plate Requirements:

  • Must show manufacturer's name, capacity, dimensions, and other purchaser-required details.
  • Should be prominently visible and properly attached.

• Identification Marks:

  • Indelible marks by supplier to aid erection, site fabrication, and installation.

Key Tables & Specifications

1. Minimum Nominal Thickness of Plates (Clause 6.3)

2. Tank Dimensions & Capacities (Examples)

IS 804 - Information to be Supplied by Purchaser (Appendix A, Clause 0.5)

Purchaser must provide the following key details when ordering tanks:

• Type of tank: Type 1, 2, or 3; cover type; number, position, and type of manholes.
• Capacity or dimensions: Litres or multiples of 1.25 m (length, breadth, depth).
• Site conditions: Space, accessibility, indoor/outdoor erection, partitions.
• Liquid properties: Nature, specific gravity, corrosiveness, hardness (if water), max temperature, boiling point.
• Special requirements: Jointing material, internal/external coatings or lagging.
• Connections: Type, number, location with sketches.
• Access: External ladders if required.
• Support structure: Details and height above ground.
• Transverse supports: Span and end support details.
• Inspection & testing: Whether purchaser’s representative will inspect, and site conditions for erection/testing.

Key Tables for Tank Dimensions & Capacities

(For tanks 5 m deep, plate thickness 5–8 mm)

Summary Diagram of Information Flow

flowchart TD
    A[Purchaser] --> B