BS 4504 Flanges

Super Industries
“Global Manufacturer of Heavy & Custom Engineered Fasteners for Oil & Gas, Power & EPC Contractors.”

1. Industry Context & System Relevance

Role of BS 4504 Flanges in Pressure Piping Systems

BS 4504 Flanges are integral components within pressure-retaining piping systems, enabling mechanically bolted connections between pipes, valves, pumps, and process equipment. These flanges provide a detachable joint that maintains system integrity under internal pressure, temperature variation, and mechanical loading.

Within engineered piping systems, flanges serve three primary functional roles:

1. Pressure containment interface
2. Mechanical alignment and support
3. Maintenance access point

Unlike permanent welded joints, flanged connections introduce controlled separability, allowing dismantling without structural damage to adjoining components.

Application Across Industrial Sectors

BS 4504 Flanges are deployed across multiple high-dependency industrial sectors:

Oil & Gas

• Upstream gathering lines
• Refinery process units
• Offshore modules
• LNG transfer systems

Refineries & Petrochemicals

• Reactor inlet/outlet lines
• Heat exchanger connections
• Storage tank nozzles

Power Generation

• Boiler feedwater systems
• Steam distribution lines
• Cooling water circuits

Water & Wastewater

• Pumping stations
• Treatment plant manifolds
• Transmission pipelines

Chemical Processing

• Corrosive fluid handling systems
• High-temperature reaction loops

Infrastructure Pipelines

• Municipal water supply
• Industrial utility corridors

Why Flanged Joints Are Preferred

In engineered systems, flanged joints are selected over welded or threaded alternatives due to:

1. Maintenance Accessibility

• Enables non-destructive disassembly
• Facilitates inspection of internal components
• Supports periodic gasket replacement

2. Alignment Flexibility

• Allows minor angular and axial adjustments
• Reduces installation stress during field fit-up

3. Equipment Interface Compatibility

• Standardized interface for pumps, valves, and vessels
• Enables modular system construction

4. Inspection & Compliance

• Visual inspection of sealing surfaces
• Ease of NDT access for bolting components

5. Replacement Efficiency

• Rapid replacement of damaged components
• Minimizes downtime in critical systems

2. Technical Definition of BS 4504 Flanges

Standardized Pressure-Retaining Components

BS 4504 Flanges are circular metallic components manufactured in accordance with the British Standard BS 4504, designed to:

• Withstand internal pressure loads
• Provide bolted mechanical connections
• Enable gasket-based sealing between mating surfaces

Core Structural Elements

A typical BS 4504 flange consists of:

• Flange ring (body)
• Bolt holes (equally spaced)
• Sealing face (FF or RF)
• Hub (for weld neck type)
• Raised or flat contact surface

PN Pressure Rating System

BS 4504 flanges are classified using the PN (Pressure Nominal) system:

PN Rating	Pressure (Bar)	Typical Application
PN6	6 bar	Low-pressure water systems
PN10	10 bar	Utility pipelines
PN16	16 bar	General industrial service
PN25	25 bar	Process piping
PN40	40 bar	High-pressure applications

Key Engineering Note:
PN rating represents maximum allowable pressure at ambient temperature, subject to derating at elevated temperatures.

Flange Face Types

Flat Face (FF)

• Entire flange surface is planar
• Used with full-face gaskets
• Preferred for:
  • Cast iron systems
  • Low-pressure applications

Raised Face (RF)

• Elevated sealing surface
• Concentrates gasket load within a defined area
• Preferred for:
  • Higher pressure services
  • Improved sealing efficiency

Flange Types under BS 4504

Slip-On Flange

• Pipe inserted into bore
• Fillet welded internally and externally
• Suitable for moderate pressure systems

Weld Neck Flange

• Long tapered hub
• Butt-welded to pipe
• Superior for:
  • High pressure
  • Cyclic loading
  • Thermal expansion environments

Blind Flange

• Solid disc without bore
• Used for:
  • Line termination
  • Pressure testing

Plate Flange

• Flat plate machined with bolt holes
• Economical for low-pressure applications

BS 4504 vs EN 1092-1

Parameter	BS 4504	EN 1092-1
Status	Legacy British Standard	Current European Standard
Dimensional Basis	Metric PN system	Metric PN system
Global Usage	Existing installations, legacy projects	New EPC projects
Interchangeability	Limited	Preferred modern standard

Engineering Clarification:
Although EN 1092-1 has largely replaced BS 4504, BS 4504 Flanges remain relevant in:

• Brownfield upgrades
• Maintenance of legacy systems
• Projects specifying British standards

Non-Interchangeability with ASME Standards

BS 4504 flanges are not dimensionally interchangeable with ASME standards such as:

• Bolt circle diameter differences
• Bolt hole count variation
• Facing geometry mismatch

Mixing standards introduces:

• Misalignment
• Uneven gasket compression
• Potential leakage or failure

3. Engineering & Sealing Principle

Fundamental Sealing Mechanism

The sealing capability of BS 4504 Flanges is governed by:

Bolt-induced compressive force acting on a deformable gasket to create a pressure-tight seal

Bolt Preload Mechanics

When bolts are tightened:

• Tensile force is induced in the bolt
• Compressive force is transferred across flange faces
• Gasket is compressed between mating surfaces

This preload must:

• Exceed internal pressure forces
• Maintain sealing under operating conditions

Gasket Compression Behavior

Gaskets function by:

• Filling microscopic surface irregularities
• Creating a fluid-tight barrier

Critical parameters:

• Seating stress (initial compression)
• Operating stress retention
• Elastic recovery

Sealing Stress Requirement

To maintain sealing:

\[
\sigma_g \geq \frac{P \cdot A_i}{A_g}
\]

Where:

• ( \sigma_g ) = gasket stress
• ( P ) = internal pressure
• ( A_i ) = internal pressure area
• ( A_g ) = gasket contact area

Flange Face Finish Impact

Surface roughness directly affects sealing:

Surface Finish (Ra)	Application
3.2 – 6.3 µm	Soft gaskets
1.6 – 3.2 µm	Metallic gaskets
Serrated finish	Improved grip and sealing

Excessively smooth surfaces reduce gasket grip, while rough surfaces cause leakage paths.

Pressure Containment Theory

Internal pressure generates:

• Axial force attempting to separate flanges
• Radial stress on gasket

Bolting system must counteract:

\[
F_{bolt} \geq F_{pressure}
\]

Where:

\[
F_{pressure} = P \times A
\]

Leakage Prevention Mechanism

Leakage is prevented by:

1. Maintaining sufficient gasket stress
2. Preventing flange rotation
3. Ensuring uniform bolt preload
4. Controlling surface finish

Failure occurs when:

• Gasket stress falls below sealing threshold
• Uneven bolt tightening introduces distortion
• Thermal or cyclic loads relax preload

4. Pressure & Load Engineering

PN Rating Engineering Framework

The PN system provides a pressure classification, but actual allowable pressure depends on:

• Material strength
• Temperature
• Flange geometry

Static vs Cyclic Loading

Static Loads

• Constant pressure systems
• Predictable stress behavior

Cyclic Loads

• Pressure fluctuations
• Thermal expansion cycles
• Cause:
  • Bolt fatigue
  • Gasket creep relaxation

Thermal Expansion Effects

Temperature variation leads to:

• Differential expansion between:
  • Pipe
  • Flange
  • Bolts

Consequences:

• Loss of preload
• Flange distortion
• Leakage risk

Pipeline Vibration Impact

Vibration introduces:

• Dynamic loading
• Bolt loosening risk
• Micro-movement at gasket interface

Mitigation:

• Proper torqueing
• Locking mechanisms
• Periodic inspection

Safety Factor Philosophy

Design incorporates safety factors to account for:

• Material variability
• Installation inaccuracies
• Operational uncertainties

Typical approach:

• Bolt stress below yield limit
• Gasket stress within allowable range

Gasket Seating Stress

Initial bolt tightening must achieve:

• Minimum seating stress
• Uniform compression

Insufficient seating leads to:

• Immediate leakage
• Poor long-term performance

Flange Rotation Consideration

Under load:

• Flanges tend to rotate about gasket centerline
• Causes:
  • Uneven gasket stress
  • Edge leakage

Design controls:

• Flange thickness
• Bolt spacing
• Hub reinforcement (for weld neck)

Dimensional & Design Logic

Critical Dimensional Parameters

Bolt Circle Diameter (BCD)

• Defines bolt positioning
• Ensures uniform load distribution

Number of Bolt Holes

• Increases with diameter and pressure rating
• Balances load per bolt

Flange Thickness

• Controls resistance to bending and rotation

Hub Dimensions (Weld Neck)

• Provides stress transition
• Reduces fatigue concentration

Face Geometry

• Flatness tolerance critical for sealing
• Parallelism between mating faces required

Tolerance & Geometric Controls

Parameter	Control Requirement
Flatness	Within specified microns
Concentricity	Bore aligned with bolt circle
Parallelism	Uniform face alignment
Bolt hole alignment	Accurate spacing

Engineering Outcome

Proper dimensional control ensures:

• Uniform bolt preload
• Stable gasket compression
• Long-term sealing reliability

5. Applicable Standards (CRITICAL SECTION)

Primary Standard — BS 4504

BS 4504 Flanges are manufactured in accordance with British Standard BS 4504, which defines:

• PN pressure rating classification (PN6 to PN40)
• Dimensional requirements:
  • Outside diameter
  • Bolt circle diameter (BCD)
  • Number and size of bolt holes
  • Flange thickness
• Facing types (Flat Face / Raised Face)
• Tolerance limits for machining and geometry

This standard establishes dimensional uniformity and interchangeability within systems designed under British engineering practice.

EN 1092-1 (Modern Equivalent)

EN 1092-1 represents the current European standard replacing BS 4504 in most new EPC projects.

Parameter	BS 4504	EN 1092-1
Standard Origin	British	European (EN)
Dimensional Structure	Metric PN	Metric PN
Usage	Legacy / existing systems	New design & EPC projects
Interchangeability	Limited	Preferred

Engineering Note:
While dimensions are often similar, full interchangeability is not guaranteed due to:

• Facing differences
• Tolerance variations
• Updated material requirements

DIN Flange Standards

DIN standards (e.g., DIN 2501, now largely superseded by EN 1092-1) historically align with:

• Metric PN classification
• Similar dimensional philosophy

BS 4504 flanges may interface with DIN systems only after dimensional verification.

ASTM Material Standards

Material compliance for BS 4504 Flanges is governed by ASTM specifications:

• ASTM A105 — Carbon steel forgings
• ASTM A350 LF2 — Low-temperature carbon steel
• ASTM A182 F304 / F316 — Stainless steel
• ASTM A182 F11 / F22 — Alloy steel
• Duplex grades — As per ASTM A182 / A240

These standards define:

• Mechanical properties
• Chemical composition
• Heat treatment conditions
• Testing requirements

Comparison with ASME B16.5

Parameter	BS 4504	ASME B16.5
Pressure System	PN (metric)	Class (150–2500)
Dimensions	Metric	Inch-based
Bolt Patterns	Different	Different
Interchangeability	Not compatible	Not compatible

Critical Engineering Statement:
BS 4504 flanges must not be interchanged with ASME B16.5 flanges due to:

• Bolt misalignment
• Sealing failure risk
• Non-uniform load distribution

Standards Mapping for Engineering Selection

Requirement	Applicable Standard
Dimensional control	BS 4504
Modern compliance	EN 1092-1
Material specification	ASTM
Pressure system reference	PN rating
Inspection certification	EN 10204

6. Material & Grade Options

Material selection for BS 4504 Flanges is governed by:

• Pressure rating (PN class)
• Operating temperature
• Corrosive environment
• Mechanical loading conditions

Carbon Steel Grades

ASTM A105

• Standard forging grade
• Suitable for:
  • Ambient to moderate temperatures
  • Non-corrosive environments
• High strength and machinability

ASTM A350 LF2

• Low-temperature carbon steel
• Improved notch toughness
• Suitable for:
  • Sub-zero service
  • Cryogenic-adjacent applications

Stainless Steel Grades

ASTM A182 F304

• General-purpose stainless steel
• Good corrosion resistance
• Suitable for:
  • Water systems
  • Mild chemical exposure

ASTM A182 F316

• Molybdenum-enhanced stainless steel
• Improved resistance to:
  • Chlorides
  • Marine environments
• Preferred in:
  • Offshore systems
  • Chemical processing

Alloy Steel Grades

ASTM A182 F11 / F22

• Chromium-molybdenum alloy steels
• High-temperature strength
• Used in:
  • Power plants
  • Steam systems

Duplex & Super Duplex Stainless Steel

• Dual-phase microstructure (austenitic + ferritic)
• High strength and corrosion resistance
• Excellent for:
  • Seawater exposure
  • Aggressive chemical environments

Material Comparison Table)

Grade	Yield Strength (MPa)	Tensile Strength (MPa)	Temperature Range	Corrosion Resistance	Typical Industry Use
ASTM A105	~250	485–620	-20°C to 425°C	Low	Oil & gas, general piping
ASTM A350 LF2	~250	485–620	-46°C to 400°C	Low	Low-temperature service
F304	~205	515–720	-196°C to 870°C	Moderate	Water, chemicals
F316	~205	515–720	-196°C to 870°C	High	Marine, chemical
F11	~275	415–585	Up to 550°C	Moderate	Power plants
F22	~415	585–760	Up to 600°C	Moderate	High-temp service
Duplex	~450	620–880	-50°C to 300°C	Very High	Offshore, desalination

7. Heat Treatment Information

Heat treatment is applied to achieve:

• Required mechanical properties
• Microstructural stability
• Residual stress reduction

Common Heat Treatment Processes

Normalizing

• Heating above critical temperature
• Air cooling
• Refines grain structure
• Improves uniformity

Quenching & Tempering

• Rapid cooling (quenching)
• Followed by reheating (tempering)
• Enhances:
  • Strength
  • Toughness
• Used for alloy steels

Solution Annealing (Stainless Steel)

• Heating to high temperature
• Rapid cooling
• Restores corrosion resistance
• Dissolves carbides

Stress Relieving

• Low-temperature heat treatment
• Reduces residual stresses from:
  • Forging
  • Machining

Mechanical Property Control

Property	Controlled By
Hardness	Heat treatment cycle
Grain size	Cooling rate
Toughness	Tempering
Ductility	Annealing

Hardness Ranges (Typical)

• Carbon steel: 120–200 HB
• Alloy steel: 150–250 HB
• Stainless steel: 150–220 HB

Impact Testing (Charpy V-Notch)

Applied for:

• Low-temperature applications
• Critical pressure systems

Ensures:

• Resistance to brittle fracture
• Compliance with project specifications

8. Manufacturing Process

Manufacturing of BS 4504 Flanges follows a controlled, traceable sequence to ensure dimensional accuracy and mechanical integrity.

Step-by-Step Process Flow

1. Raw Material Inspection

• Verification of:
  • Mill Test Certificates (MTC)
  • Chemical composition
• Identification marking for traceability

2. Forging / Plate Cutting

Forged Flanges:

• Billet heating
• Closed-die or open-die forging
• Grain flow aligned with geometry

Plate Flanges:

• CNC profile cutting from plate
• Used for lower pressure classes

3. Heat Treatment (Initial)

• Applied post-forging
• Ensures uniform structure

4. CNC Machining

• Turning operations:
  • Outer diameter
  • Bore diameter
• Machining tolerances maintained

5. Drilling

• Bolt holes drilled using CNC indexing
• Ensures:
  • Accurate pitch circle
  • Angular spacing

6. Facing Operation

• Machining of sealing surface:
  • Flat Face or Raised Face
• Surface finish controlled (Ra values)

7. Secondary Heat Treatment

• As per material specification
• Final mechanical property adjustment

8. Surface Coating / Treatment

• Application based on material and environment

9. Final Inspection

• Dimensional verification
• NDT testing (as required)

10. Marking & Traceability

• Heat number
• Material grade
• Size and PN rating
• Manufacturer identification

Surface Finish Options

Surface finish impacts:

• Corrosion resistance
• Gasket sealing performance

Available Surface Treatments

Anti-Rust Oil Coating

• Temporary protection
• Used for carbon steel during storage

Black Coating

• Oxide layer formation
• Moderate corrosion resistance

Zinc Plating

• Electroplated zinc layer
• Protection in humid environments

Hot-Dip Galvanizing

• Thick zinc coating
• Suitable for:
  • Outdoor exposure
  • Water systems

Passivation (Stainless Steel)

• Chemical treatment
• Removes free iron
• Enhances corrosion resistance

Surface Roughness (Ra Values)

Finish Type	Ra Value	Application
Smooth finish	1.6–3.2 µm	Metallic gaskets
Serrated finish	3.2–6.3 µm	Soft gaskets
Rough finish	>6.3 µm	Limited use

Gasket Seating Implications

• Lower Ra → better for metallic gaskets
• Higher Ra → better grip for soft gaskets
• Incorrect finish → leakage risk

A. Technical Dimension Tables — BS 4504 Flanges

The following table provides representative dimensional data for BS 4504 Flanges across common DN sizes and PN ratings. Final dimensions must always be verified against project specifications and approved drawings.

Table A1 — Dimensional Reference (PN16 Series)

DN (mm)	Outside Diameter (mm)	BCD (mm)	Bolt Holes	Bolt Size	Flange Thickness (mm)
15	95	65	4	M12	12
25	115	85	4	M12	14
50	165	125	4	M16	16
80	200	160	8	M16	18
100	220	180	8	M16	18
150	285	240	8	M20	20
200	340	295	12	M20	22
300	455	410	12	M24	28
400	580	525	16	M27	32
600	840	770	20	M33	36

Engineering Observations

• Increase in bolt count and diameter ensures uniform load distribution
• Flange thickness increases to resist bending and rotation
• BCD growth maintains bolt stress within allowable limits

B. Pressure Rating Table (PN System)

Table B1 — PN Rating vs Pressure

PN Rating	Pressure (bar)	Pressure (MPa)	Typical Service
PN6	6	0.6	Water pipelines
PN10	10	1.0	Utility systems
PN16	16	1.6	General industrial
PN25	25	2.5	Process piping
PN40	40	4.0	High-pressure systems

Temperature Derating Consideration

Actual allowable pressure reduces with temperature due to:

• Reduction in material yield strength
• Increased creep effects (at elevated temperature)

C. Torque Chart

Bolt torque values are influenced by:

• Bolt material grade
• Lubrication condition
• Desired preload

Table C1 — Recommended Torque Values

Bolt Size	Grade 8.8 (Dry) Nm	Grade 8.8 (Lubricated) Nm	Grade 10.9 (Dry) Nm	ASTM B7 (Lubricated) Nm
M12	80	60	110	95
M16	200	150	280	240
M20	400	300	550	480
M24	700	520	950	820
M27	1000	750	1350	1150
M30	1350	1000	1800	1550
M33	1800	1350	2400	2100

Engineering Notes

• Lubrication reduces friction → increases preload consistency
• Torque scatter must be considered (±10–15%)
• Final torque values should align with project specifications

D. Preload Calculation Guide

1. Fundamental Bolt Load Equation

F = P \times A

Where:

• ( F ) = force due to internal pressure
• ( P ) = internal pressure
• ( A ) = internal cross-sectional area

2. Bolt Stress Equation

\[
\sigma_b = \frac{F_b}{A_b}
\]

Where:

• ( \sigma_b ) = bolt stress
• ( F_b ) = bolt preload force
• ( A_b ) = tensile stress area of bolt

3. Torque–Preload Relationship

\[
T = K \times F \times d
\]

Where:

• ( T ) = torque
• ( K ) = friction factor (0.15–0.25)
• ( F ) = preload force
• ( d ) = bolt diameter

4. Sample Calculation

Given:

• Pressure = 16 bar (1.6 MPa)
• Pipe ID = 200 mm
• Bolt size = M20
• Number of bolts = 12

Step 1: Calculate Area

\[
A = \frac{\pi D^2}{4} = \frac{3.14 \times (0.2)^2}{4} = 0.0314 \, m^2
\]

Step 2: Force Due to Pressure

\[
F = P \times A = 1.6 \times 10^6 \times 0.0314 = 50{,}240 \, N
\]

Step 3: Load Per Bolt

\[
F_{bolt} = \frac{50{,}240}{12} \approx 4{,}187 \, N
\]

Step 4: Apply Safety Factor (×2 to ×3)

\[
F_{design} \approx 10{,}000 \, N \text{ per bolt}
\]

Step 5: Torque Estimation

\[
T = 0.2 \times 10{,}000 \times 0.02 = 40 \, \text{Nm}
\]

Engineering Conclusion

• Preload must exceed pressure-induced separation force
• Actual torque values must align with gasket requirements

E. Mechanical Property Table

Table E1 — Mechanical Properties

Material	Yield Strength (MPa)	Tensile Strength (MPa)	Elongation (%)	Hardness (HB)	Impact Value
A105	250	485–620	20	120–180	Moderate
LF2	250	485–620	22	120–180	High (low temp)
F304	205	515–720	40	150–200	High
F316	205	515–720	40	150–220	High
F11	275	415–585	18	140–200	Moderate
F22	415	585–760	16	160–220	Moderate

F. Corrosion Resistance Comparison Table

Table F1 — Environmental Suitability

Material	Marine	Acidic	Humid	Hydrocarbon
Carbon Steel	Poor	Poor	Moderate	Good
SS304	Moderate	Moderate	Good	Good
SS316	Good	Good	Excellent	Good
Alloy Steel	Moderate	Poor	Moderate	Excellent
Duplex	Excellent	Excellent	Excellent	Excellent

9. Inspection & Quality Control

Inspection of BS 4504 Flanges ensures compliance with dimensional, mechanical, and material requirements.

Non-Destructive Testing (NDT)

Positive Material Identification (PMI)

• Verifies alloy composition
• Ensures correct material grade

Ultrasonic Testing (UT)

• Detects internal defects
• Applicable for forged flanges

Magnetic Particle Inspection (MPI)

• Detects surface/subsurface cracks
• Used for carbon and alloy steel

Dye Penetrant Inspection (DPI)

• Detects surface defects
• Used for stainless steel

Hydrostatic Testing

• Validates pressure containment capability
• Conducted as per project requirements

Dimensional Inspection

Verification of:

• Outer diameter
• Bore diameter
• Bolt circle diameter
• Hole alignment
• Face flatness

Certification

EN 10204 3.1

• Manufacturer certification
• Chemical & mechanical test results

EN 10204 3.2

• Third-party inspection validation
• Independent verification body

Traceability System

Each flange is marked with:

• Heat number
• Material grade
• Size and PN rating
• Manufacturer identification

Ensures:

• Full traceability from raw material to dispatch

10. Industries Served

BS 4504 Flanges are deployed across sectors where pressure containment, system reliability, and maintainability are critical. Selection is driven by PN rating, material compatibility, and service conditions.

Oil & Gas (Upstream, Midstream, Downstream)

Applications

• Wellhead flowlines
• Gathering and transmission pipelines
• Refinery process units
• Tank farm connections

Engineering Requirements

• Resistance to hydrocarbons and sour service (when specified)
• Compatibility with process piping standards
• Controlled bolt preload for leak-tight joints

Material Preference

• Carbon steel (A105) for general service
• Stainless steel / Duplex for corrosive environments

Refineries & Petrochemical Plants

Applications

• Heat exchangers
• Distillation columns
• Reactor piping
• Utility manifolds

Engineering Considerations

• Elevated temperature performance
• Chemical compatibility
• Cyclic loading resistance

Power Generation (Thermal / Combined Cycle)

Applications

• Boiler feedwater systems
• Steam pipelines
• Cooling water circuits

Engineering Considerations

• Thermal expansion management
• High-temperature alloy steel usage (F11 / F22)
• Long-term creep resistance

Chemical Processing Plants

Applications

• Acid handling systems
• Solvent transfer lines
• Reaction loops

Engineering Considerations

• Corrosion resistance
• Gasket compatibility
• Material stability under chemical exposure

Water & Wastewater Systems

Applications

• Pump stations
• Treatment plant piping
• Municipal transmission lines

Engineering Considerations

• Corrosion protection (coatings / galvanizing)
• Long-term exposure to moisture
• Ease of maintenance

Infrastructure & Utility Pipelines

Applications

• District cooling systems
• Industrial utility corridors
• Firewater systems

Engineering Considerations

• Reliability under continuous service
• Standardization for maintenance efficiency

11. Export Capability & Global Supply

Super Industries manufactures and supplies BS 4504 Flanges for international EPC projects with structured export execution aligned to project documentation requirements.

Export Regions

• United States
• European Union
• Middle East (GCC countries)
• Southeast Asia
• Africa (project-based supply)

Packaging Standards

• Wooden crates (ISPM-15 compliant)
• Palletized loads with moisture protection
• Individual flange protection for sealing faces
• Rust preventive application for carbon steel

Documentation Package

Supplied documentation typically includes:

• Commercial invoice
• Packing list
• Mill Test Certificates (EN 10204 3.1 / 3.2)
• Inspection reports
• Dimensional inspection records
• NDT reports (if applicable)
• Certificate of origin

Logistics Coordination

• Coordination with EPC procurement schedules
• Port handling and containerization
• Marking aligned with project tagging systems
• Support for multi-location dispatches

Project Supply Capability

• Bulk supply aligned with project timelines
• Lot traceability for each batch
• Capability to support shutdown and maintenance schedules
• Integration with EPC vendor documentation systems

12. PROCUREMENT & INSTALLATION VIEW

Bolt Tightening Sequence (Cross Pattern)

Proper tightening sequence ensures:

• Uniform gasket compression
• Prevention of flange distortion

Recommended Method

1. Initial hand tightening
2. Star (cross) pattern tightening
3. Incremental torque application (30% → 60% → 100%)

Torque Application Stages

Stage	Torque Level	Purpose
Stage 1	30%	Initial seating
Stage 2	60%	Intermediate alignment
Stage 3	100%	Final preload
Stage 4	Circular pass	Uniform stress distribution

Re-Torque Practice

• Conducted after initial pressurization or thermal cycling
• Compensates for:
  • Gasket creep
  • Bolt relaxation

Gasket Selection & Replacement

Selection Criteria

• Pressure class (PN rating)
• Temperature range
• Chemical compatibility

Common Gasket Types

• Non-asbestos fiber
• Spiral wound
• PTFE-based

Replacement Guidelines

• Replace after disassembly
• Inspect flange face for damage
• Verify surface finish before installation

Field Inspection Checklist

Before commissioning:

• Verify flange alignment
• Confirm bolt grade and size
• Check torque values
• Inspect gasket installation
• Ensure no visible flange distortion

Storage Practices

• Store in dry, covered environment
• Protect flange faces with covers
• Avoid direct ground contact
• Maintain traceability markings

13. CUSTOM ENGINEERING CAPABILITIES

Super Industries supports project-specific requirements for BS 4504 Flanges within defined engineering and manufacturing limits.

Non-Standard Sizes

• Custom DN beyond standard range
• Adaptation for project-specific piping systems

Special Drilling Patterns

• Non-standard bolt hole configurations
• Matching with legacy equipment

High-Thickness Flanges

• Designed for:
  • High-pressure applications
  • Structural reinforcement

Coating Customization

• Project-specific coating systems
• Compliance with environmental exposure conditions

Project-Specific Marking

• Tag numbers
• Heat numbers
• Client-specific identification formats

ENGINEERING SUMMARY

BS 4504 Flanges provide a standardized, pressure-rated, bolted connection system suitable for:

• Controlled disassembly
• Reliable gasket-based sealing
• Compatibility with legacy British-standard piping systems

Their continued application in global projects is driven by:

• Installed base requirements
• Maintenance of existing systems
• Project specifications referencing BS standards

FINAL ENGINEERING CONCLUSION

From an EPC evaluation perspective, BS 4504 Flanges must be assessed on:

• Compliance with dimensional standards
• Material traceability and certification
• Manufacturing control and inspection protocols
• Suitability for pressure, temperature, and environmental conditions

Super Industries manufactures these flanges in alignment with:

• BS dimensional requirements
• ASTM material standards
• EN inspection and certification practices

This ensures that supplied components are suitable for:

• Integration into pressure piping systems
• Third-party inspection acceptance
• Global project procurement environments

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