BS10 FLANGES

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

1. Industry Context & System Relevance

BS10 Flanges are a legacy yet operationally relevant flange system used across low to medium pressure piping networks, particularly in regions and industries influenced by British engineering standards. Their continued use is not incidental—it is driven by installed base compatibility, system continuity, and suitability for moderate-duty service conditions.

Functional Role in Piping Systems

BS10 Flanges provide a detachable mechanical joint for piping systems, enabling:

• Assembly and disassembly for maintenance
• Equipment integration (valves, pumps, strainers)
• Controlled sealing under moderate pressure conditions
• Alignment of piping segments

They are primarily deployed where ease of installation and cost-efficiency outweigh high-pressure performance requirements.

Application Domains

BS10 Flanges are commonly applied in:

Water Treatment Plants

• Raw water intake lines
• Filtration units
• Chemical dosing systems

Marine & Shipbuilding

• Ballast systems
• Cooling water circuits
• Bilge and discharge piping

Fire Protection Systems

• Hydrant lines
• Sprinkler systems
• Pump discharge networks

HVAC Systems

• Chilled water pipelines
• Condenser circuits
• Air handling units

Power Plants (Auxiliary Systems)

• Cooling water lines
• Low-pressure steam drains
• Service water networks

General Industrial Piping

• Utility lines (air, water, low-pressure fluids)
• Process lines with non-critical pressure conditions

Legacy System Relevance

BS10 Flanges are prevalent in:

• Commonwealth countries
• Older infrastructure installations
• Marine vessels built under British classification systems

Their continued use is driven by:

• Interchangeability within existing systems
• Availability of matching components
• Cost-effective replacement strategy

Comparison with ANSI/ASME Systems

Parameter	BS10 Flanges	ANSI/ASME Flanges
Pressure Rating	Table-based	Class-based (150, 300, etc.)
Sealing Type	Flat Face	Raised Face / RTJ
Pressure Range	Low to Moderate	Medium to High
Standardization	Dimensional tables	Pressure-temperature ratings
Application	Utilities, marine, water	Oil & gas, high pressure systems

Engineering Note:
BS10 Flanges are not designed for high-pressure or high-temperature applications where ASME B16.5 or B16.47 systems are required.

Pressure & Temperature Suitability

Typical operating conditions:

• Pressure: Up to ~20 bar (depending on table)
• Temperature: Ambient to moderate (~200°C depending on material)

Their suitability is limited by:

• Flat face sealing constraints
• Lower bolt load capacity
• Reduced flange thickness

2. Technical Definition

BS10 Flanges are defined as:

A British Standard flange system where pressure ratings are indirectly defined through dimensional tables (Table A, B, C, D, E, F, H, J, etc.), rather than explicit pressure-temperature ratings.

Table-Based Classification System

Each BS10 table defines:

• Flange outer diameter (OD)
• Bolt circle diameter (PCD)
• Number of bolt holes
• Bolt size
• Flange thickness

Typical Table Hierarchy

Table	Relative Pressure Capacity
A	Very low
B	Low
C	Low
D	Moderate
E	Moderate
F	Medium
H	Medium-high
J	Highest within BS10

Pressure vs Table Relationship

BS10 does not explicitly define pressure ratings. However, industry approximations exist:

• Table D: ~7–10 bar
• Table E: ~10–16 bar
• Table F: ~16–20 bar

These values depend on:

• Material grade
• Temperature
• Gasket type
• Bolt preload

Flange Type Characteristics

• Face Type: Flat Face (FF)
• Sealing: Gasket-based
• Connection: Bolted joint
• Surface Finish: Smooth or serrated

3. Engineering & Sealing Principle

Load Transfer Mechanism

The integrity of a BS10 flange joint is governed by:

1. Bolt preload application
2. Gasket compression
3. Flange face contact

The bolts apply axial force, compressing the gasket between two flat flange faces.

Gasket Compression Theory

The gasket acts as a deformable sealing element:

• Initial compression fills surface irregularities
• Elastic recovery maintains sealing under pressure
• Compression must exceed internal pressure force

Typical gasket types:

• Non-asbestos fiber
• Rubber
• PTFE

Flat Face Sealing Behavior

Unlike raised face flanges:

• Entire flange face is in contact
• Load is distributed uniformly
• Lower stress concentration

However:

• Requires careful alignment
• Sensitive to uneven bolt tightening

Bolt Preload Logic

Bolt preload must:

• Exceed internal pressure force
• Maintain gasket compression
• Prevent joint separation

Key factors:

• Bolt diameter
• Material grade
• Lubrication condition

Leakage Prevention Principles

Leakage is prevented when:

• Gasket stress > internal fluid pressure
• Flange faces remain parallel
• Bolt preload is uniformly distributed

Failure modes include:

• Under-tightening → leakage
• Over-tightening → gasket crushing
• Uneven tightening → flange distortion

4. Pressure & Load Engineering

Static Load Conditions

BS10 Flanges are designed for:

• Internal pressure loading
• Bolt tensile loading
• Gasket compression forces

They are suitable for:

• Steady-state flow systems
• Non-cyclic operations

Dynamic Load Limitations

BS10 Flanges are not recommended for:

• High-frequency pressure fluctuations
• Hydraulic shock systems
• Pulsating loads

Reason:

• Lower flange rigidity
• Reduced bolt load capacity
• Flat face sealing limitations

Stress Limitations

Compared to ANSI/ASME:

• Lower allowable stress
• Reduced safety margins
• No defined pressure-temperature curves

Safety Factor Considerations

Typical design safety approach:

• Conservative table selection
• Oversizing where required
• Material selection based on environment

Unsuitability for High-Pressure Systems

BS10 Flanges should not be used in:

• Hydraulic systems (>20 bar)
• High-temperature steam lines
• Critical oil & gas pipelines

Limitations arise from:

• Flat face design
• Limited bolt preload capacity
• Lack of standardized pressure rating curves

Dimensional & Design Logic

Key Dimensional Parameters

Each BS10 flange includes:

• Outer Diameter (OD)
• Pitch Circle Diameter (PCD)
• Number of Bolt Holes
• Bolt Hole Diameter
• Flange Thickness
• Nominal Bore (NB)

Table-Based Standardization

Dimensions are fixed per table:

• Ensures compatibility within same table
• Prevents cross-table interchangeability

Tolerance Philosophy

• Machining tolerances applied to OD, bore, and PCD
• Bolt hole alignment critical for installation
• Face flatness influences sealing performance

Interchangeability Limitations

• Table D flange ≠ Table E flange
• BS10 ≠ ANSI compatibility
• Requires strict adherence to table designation

Face Design

• Flat Face (FF) standard
• Surface finish affects gasket seating
• No raised face or RTJ provision

5. Applicable Standards

BS10 Flanges are governed by a combination of dimensional standards, material specifications, and inspection protocols. While BS10 defines geometry, it does not independently define material grades or pressure-temperature ratings. Therefore, cross-referencing with other standards is mandatory for EPC-level compliance.

Primary Dimensional Standard

BS10 (British Standard Table of Flanges)

Defines:

• Flange dimensions based on tables (A, B, C, D, E, F, H, J)
• Bolt circle diameter (PCD)
• Number of bolt holes
• Flange thickness
• Nominal bore compatibility

Engineering Implication:

BS10 is a dimensional standard, not a full design code. Pressure capability must be evaluated separately based on material and service conditions.

Relevant International Standards (Cross-Reference)

BS EN 1092-1

• European flange standard replacing older BS systems
• Defines pressure classes (PN6, PN10, PN16, etc.)
• Used for comparison and partial equivalence

Comparison Context:

BS10 Table	Approximate EN Equivalent
Table D	PN6 / PN10
Table E	PN10 / PN16
Table F	PN16

Note: Direct interchangeability is not guaranteed due to dimensional differences.

ASTM Material Standards

Material selection for BS10 Flanges is typically aligned with:

• ASTM A105 → Carbon steel forging
• ASTM A350 LF2 → Low-temperature carbon steel
• ASTM A182 F304 / F316 → Stainless steel forgings

DIN / EN Equivalence

• DIN 2573 / 2576 (PN6 / PN10) used for approximate comparison
• EN standards used in export documentation

Engineering Constraint:

Dimensional mismatch prevents direct substitution without verification.

Standard Selection in EPC Projects

Selection depends on:

• Project specification
• Client standardization
• Operating pressure & temperature
• Regional compliance requirements

6. Material & Grade Options

Material selection governs:

• Pressure containment capability
• Corrosion resistance
• Temperature tolerance
• Weldability and machinability

Carbon Steel Grades

ASTM A105

• Forged carbon steel
• Suitable for ambient to moderate temperatures
• Good machinability and strength

ASTM A350 LF2

• Low-temperature carbon steel
• Improved impact resistance
• Suitable for sub-zero applications

Stainless Steel Grades

ASTM A182 F304

• Austenitic stainless steel
• General corrosion resistance
• Suitable for water and mild chemicals

ASTM A182 F316

• Molybdenum-bearing stainless steel
• Enhanced corrosion resistance
• Suitable for marine and chloride environments

Mild Steel (Low-Pressure Applications)

• Used in non-critical systems
• Lower strength compared to forged grades
• Cost-effective for utility lines

Material Comparison Table

Grade	Yield Strength (MPa)	Tensile Strength (MPa)	Temperature Range (°C)	Corrosion Resistance	Typical Use
ASTM A105	~250	~485–620	-29 to 425	Low	General industrial piping
ASTM A350 LF2	~250	~485–620	-46 to 345	Low	Low-temperature service
ASTM A182 F304	~205	~515–720	-196 to 870	Moderate	Water, chemical systems
ASTM A182 F316	~205	~515–720	-196 to 870	High	Marine, corrosive fluids
Mild Steel	~200	~400–500	0 to 300	Low	Utility pipelines

7. Heat Treatment Information

Heat treatment is applied to achieve:

• Required mechanical properties
• Grain refinement
• Residual stress reduction

Carbon Steel Heat Treatment

Normalizing

• Refines grain structure
• Improves toughness
• Ensures uniform mechanical properties

Quenching & Tempering (Q&T)

• Increases strength and hardness
• Improves fatigue resistance

Stress Relieving

• Removes residual stresses after machining
• Reduces distortion risk

Stainless Steel Heat Treatment

Solution Annealing

• Heating followed by rapid cooling
• Dissolves carbides
• Restores corrosion resistance

Hardness Ranges

Material	Typical Hardness (HB)
A105	120–180
A350 LF2	120–180
F304	150–200
F316	150–200

Microstructure Considerations

• Carbon steel: Ferrite-pearlite structure
• Stainless steel: Austenitic structure

These directly influence:

• Strength
• Ductility
• Corrosion resistance

Impact Testing (Charpy V-Notch)

Applicable for:

• Low-temperature service (A350 LF2)

Ensures:

• Resistance to brittle fracture
• Compliance with project specifications

8. Manufacturing Process

BS10 Flanges are produced through controlled and traceable manufacturing processes to ensure dimensional accuracy and material integrity.

Raw Material Inspection

• Verification of mill test certificates
• Chemical composition analysis
• Visual inspection

Forging / Plate Cutting

Forged Flanges:

• Hot forging improves grain flow
• Enhances mechanical strength

Plate-Cut Flanges:

• Used for low-pressure applications
• Machined from steel plates

CNC Machining

• Bore machining
• Outer diameter finishing
• Bolt circle precision machining

Ensures:

• Tight tolerances
• Repeatability

Drilling

• Bolt holes drilled as per PCD
• Angular spacing maintained
• Alignment critical for installation

Facing

• Flat face machining
• Surface finish control
• Ensures proper gasket seating

Heat Treatment (If Required)

• Performed post-forging or machining
• Controlled furnace cycles

Surface Coating

• Anti-corrosion treatment
• Application based on service environment

Final Inspection

• Dimensional verification
• Visual inspection
• NDT (if required)

Marking & Traceability

Each flange marked with:

• Material grade
• Heat number
• Table designation (e.g., Table D, E)
• Manufacturer identification

Ensures:

• Full traceability
• Inspection compliance

Surface Finish Options

Surface condition affects both:

• Corrosion resistance
• Sealing performance

Black Finish

• As-machined or forged surface
• Minimal protection
• Suitable for dry environments

Zinc Plating

• Electroplated coating
• Moderate corrosion protection
• Suitable for indoor applications

Hot-Dip Galvanizing (HDG)

• Thick zinc coating
• High corrosion resistance
• Suitable for outdoor and marine environments

Paint Coating

• Epoxy or industrial coatings
• Applied for project-specific requirements

Stainless Steel Passivation

• Chemical treatment
• Enhances oxide layer
• Improves corrosion resistance

Surface Roughness Consideration

• Affects gasket sealing performance
• Typical Ra values controlled during machining

9. Engineering Tables & Dimensional Data

BS10 Flanges are governed by table-based dimensional standardization, where each table defines a complete geometry set. The following tables represent commonly used configurations for EPC reference and preliminary design validation.

A. BS10 Table Dimension Chart (Representative Values)

Note: Values are indicative for engineering reference. Project-specific drawings and verified standards must be used for procurement.

Table D Flanges (Moderate Pressure – Utility Systems)

Nominal Bore (NB)	OD (mm)	PCD (mm)	Bolt Size	No. of Holes	Thickness (mm)
15 mm	95	65	M12	4	10
25 mm	115	85	M12	4	12
50 mm	165	125	M16	4	14
80 mm	200	160	M16	8	16
100 mm	220	180	M16	8	18
150 mm	285	240	M20	8	20
200 mm	340	295	M20	8	22

Table E Flanges (Higher Moderate Pressure)

Nominal Bore (NB)	OD (mm)	PCD (mm)	Bolt Size	No. of Holes	Thickness (mm)
15 mm	95	65	M12	4	12
25 mm	115	85	M12	4	14
50 mm	165	125	M16	4	16
80 mm	200	160	M16	8	18
100 mm	235	190	M20	8	20
150 mm	300	250	M20	8	22
200 mm	360	310	M24	8	24

Table F Flanges (Upper Range of BS10 Capability)

Nominal Bore (NB)	OD (mm)	PCD (mm)	Bolt Size	No. of Holes	Thickness (mm)
25 mm	115	85	M12	4	16
50 mm	165	125	M16	4	18
80 mm	210	170	M20	8	20
100 mm	250	210	M20	8	22
150 mm	320	270	M24	8	24
200 mm	380	330	M24	12	26

Dimensional Engineering Notes

• Bolt circle (PCD) governs load distribution
• Flange thickness directly impacts bending resistance
• Bolt size correlates with required preload
• Higher tables → increased rigidity and pressure tolerance

B. Pressure Rating Approximation Table

BS10 does not define pressure ratings explicitly. The following table provides engineering approximations for design evaluation.

BS10 Table	Approx Pressure (Bar)	Approx Pressure (PSI)	Typical Application	Safety Margin Consideration
Table D	7–10 bar	100–150 psi	Water systems	Moderate
Table E	10–16 bar	150–230 psi	HVAC / fire systems	Moderate
Table F	16–20 bar	230–300 psi	Industrial piping	Lower margin

Engineering Interpretation

• Values depend on material, temperature, and gasket selection
• Safety margins must be validated per project specification
• Not suitable for cyclic or surge pressure systems

C. Torque Chart (Bolt Tightening Reference)

Torque values ensure adequate preload without overstressing bolts or damaging gaskets.

Torque Values (Indicative)

Bolt Size	Bolt Grade	Dry Torque (Nm)	Lubricated Torque (Nm)
M12	8.8	70	50
M16	8.8	170	120
M20	8.8	330	230
M24	8.8	570	400

Torque Engineering Notes

• Lubrication reduces friction → lower torque required
• Over-torque can crush gasket and distort flange
• Under-torque leads to leakage

D. Preload Calculation Guide

Proper preload is critical for maintaining gasket compression and preventing leakage.

Fundamental Bolt Load Formula

   

Where:

• F = Bolt preload force (N)
• σ = Allowable bolt stress (MPa)
• A = Tensile stress area (mm²)

Torque–Preload Relationship

   

Where:

• T = Torque (Nm)
• K = Torque coefficient (≈ 0.18–0.25)
• F = Preload force (N)
• d = Bolt diameter (m)

Sample Calculation (M16 Bolt)

Assumptions:

• Bolt stress (σ) = 200 MPa
• Tensile area (A) = 157 mm²

Preload force:

• F = 200 × 157 = 31,400 N

Torque (assuming K = 0.2, d = 0.016 m):

• T = 0.2 × 31,400 × 0.016
• T ≈ 100 Nm

Engineering Considerations

• Preload must exceed internal pressure force
• Gasket seating stress must be maintained
• Safety factor typically applied (1.5–2.5)

E. Mechanical Property Table

Material	Yield Strength (MPa)	Tensile Strength (MPa)	Elongation (%)	Hardness (HB)
ASTM A105	~250	485–620	20–25	120–180
ASTM A350 LF2	~250	485–620	22–28	120–180
ASTM A182 F304	~205	515–720	30–40	150–200
ASTM A182 F316	~205	515–720	30–40	150–200

Engineering Interpretation

• Higher elongation → better ductility
• Stainless steel → superior corrosion resistance
• Carbon steel → higher load-bearing efficiency

F. Corrosion Resistance Table

Material	Marine Environment	Water Systems	Industrial Fluids
Carbon Steel	Poor	Moderate	Moderate
SS304	Moderate	Good	Moderate
SS316	Excellent	Excellent	Excellent

Material Selection Logic

• Marine: SS316 preferred
• Water systems: SS304 acceptable
• General industry: Carbon steel with coating

10. Inspection & Quality Control

Inspection ensures that BS10 Flanges meet:

• Dimensional requirements
• Material specifications
• Mechanical integrity

Positive Material Identification (PMI)

• Verifies chemical composition
• Confirms material grade (CS, SS)
• Required for critical applications

Non-Destructive Testing (NDT)

Ultrasonic Testing (UT)

• Detects internal defects
• Applicable for forged flanges

Magnetic Particle Inspection (MPI)

• Surface crack detection (carbon steel)

Dye Penetrant Inspection (DPI)

• Surface defect detection (stainless steel)

Dimensional Inspection

• OD, PCD, thickness verification
• Bolt hole alignment
• Bore concentricity

Hydrostatic Testing (If Applicable)

• Assembly-level testing
• Verifies sealing performance
• Not typically applied to individual flanges

Hardness Testing

• Confirms heat treatment effectiveness
• Ensures compliance with material standards

Documentation Standards

EN 10204 Certification

• 3.1 Certificate: Manufacturer test certificate
• 3.2 Certificate: Third-party inspection validation

Traceability Requirements

Each flange must maintain:

• Heat number traceability
• Material grade marking
• Table identification (e.g., BS10 Table E)
• Inspection records

Inspection Philosophy

• Prevention over correction
• Batch-level verification
• Compliance with EPC specifications

11. Industries Served

BS10 Flanges are deployed across sectors where moderate pressure, system compatibility, and maintenance accessibility are key design drivers.

Water Treatment & Distribution

Applications include:

• Raw water intake pipelines
• Clarification and filtration systems
• Chemical dosing lines
• Treated water distribution

Engineering Basis:

• Moderate pressure operation
• Compatibility with legacy BS piping systems
• Corrosion protection via coatings or stainless steel

Marine & Shipbuilding

Applications include:

• Ballast water systems
• Sea water cooling lines
• Bilge discharge piping

Material Selection Consideration:

• SS316 for chloride resistance
• Hot-dip galvanized carbon steel for cost-controlled systems

Fire Protection Systems

Applications include:

• Hydrant networks
• Sprinkler systems
• Pump discharge lines

Engineering Requirement:

• Reliable sealing under static pressure
• Compliance with system pressure ratings (typically ≤16 bar)

HVAC & Building Services

Applications include:

• Chilled water lines
• Condenser water systems
• Utility piping networks

Design Consideration:

• Ease of installation and maintenance
• Compatibility with low-pressure systems

Power Plants (Auxiliary Systems)

Applications include:

• Cooling water pipelines
• Service water lines
• Low-pressure steam drains

Engineering Limitation:

• Not used in high-pressure steam circuits
• Restricted to auxiliary and non-critical systems

Infrastructure & General Industry

Applications include:

• Industrial utility lines
• Process water systems
• Non-critical fluid transport

12. Procurement & Installation Engineering View

BS10 Flanges must be evaluated not only as components, but as part of a complete bolted joint system.

Gasket Selection & Placement

• Flat face flanges require full-face gaskets
• Gasket material must match:
  • Fluid compatibility
  • Temperature range
  • Pressure class

Improper gasket selection leads to:

• Leakage
• Premature failure

Bolt Tightening Sequence

A cross-pattern tightening sequence is mandatory to ensure uniform load distribution.

Typical Sequence:

1 → 3 → 5 → 7
2 → 4 → 6 → 8

Engineering Objective:

• Prevent flange distortion
• Achieve uniform gasket compression

Tightening Methodology

• Initial snug tightening
• Incremental torque application (30% → 60% → 100%)
• Final pass for uniformity

Re-Tightening Practice

• Recommended after initial pressurization
• Accounts for gasket relaxation
• Must be performed under controlled conditions

Field Inspection Requirements

Inspection during installation includes:

• Alignment verification
• Bolt torque validation
• Gasket positioning
• Surface cleanliness

Storage & Handling Guidelines

• Store in dry, covered conditions
• Protect flange faces from damage
• Apply rust preventive coatings (if carbon steel)

13. Custom Engineering Capabilities

BS10 Flanges are often adapted to project-specific requirements where standard tables require modification or enhancement.

Dimensional Customization

• Non-standard bolt drilling
• Modified PCD
• Increased flange thickness for higher rigidity

Material Upgrades

• Transition from carbon steel to stainless steel
• Low-temperature service materials
• Corrosion-resistant alloys (project-specific)

Surface Protection Customization

• Project-specific coating systems
• Multi-layer paint coatings
• Enhanced galvanizing thickness

Marking & Identification

• Client-specific tagging
• Heat number traceability
• Project code stamping

Documentation Alignment

• Compliance with EPC specifications
• Integration with inspection plans (ITP)
• Third-party inspection readiness

14. Export Capability

Super Industries supplies BS10 Flanges for international projects with structured export and compliance processes.

Regions Served

• Middle East
• Europe
• Southeast Asia
• Africa

Packaging Standards

• Wooden crates / pallets
• Moisture protection
• Individual tagging for traceability

Export Documentation

Typical documentation includes:

• Commercial invoice
• Packing list
• Mill test certificates (EN 10204 3.1 / 3.2)
• Certificate of origin
• Inspection reports

Logistics & Project Handling

• Batch segregation based on heat number
• Containerized shipment planning
• Coordination with EPC logistics teams

Compliance Documentation

• Material traceability records
• NDT reports
• Dimensional inspection reports
• Coating inspection records

Engineering Limitations & Selection Guidance

BS10 Flanges must be selected with full awareness of their limitations.

Pressure Limitation

• Suitable for low to moderate pressure systems only
• Not recommended beyond ~20 bar

Temperature Limitation

• Material-dependent
• Typically limited to moderate temperatures

Sealing Limitation

• Flat face design requires:
  • Accurate alignment
  • Proper gasket selection
  • Controlled bolt tightening

Dynamic Load Restriction

Not suitable for:

• Pulsating pressure systems
• Hydraulic shock environments
• High vibration pipelines

Interchangeability Restriction

• Not interchangeable with ANSI/ASME flanges
• Not interchangeable across BS10 tables

Engineering Summary

BS10 Flanges represent a dimensionally standardized, table-based flange system engineered for low to medium pressure applications where:

• Flat face sealing is sufficient
• System pressures remain within moderate limits
• Compatibility with existing BS infrastructure is required

Technical Positioning

• Defined by BS10 dimensional tables
• Governed by material standards (ASTM)
• Verified through inspection and testing protocols
• Applied in utility, marine, and general industrial systems

Design Philosophy

• Conservative load handling
• Simplicity in sealing mechanism
• Ease of installation and maintenance
• Compatibility-driven usage

Procurement Perspective

For EPC contractors and consultants, evaluation of BS10 Flanges should include:

• Table selection aligned with pressure requirements
• Material compatibility with service conditions
• Verification of dimensional compliance
• Inspection and certification requirements

Final Engineering Statement

BS10 Flanges are suitable for non-critical, moderate-pressure piping systems where:

• Operational conditions are stable
• Installation practices are controlled
• Design limitations are clearly understood

They are not a substitute for high-pressure flange systems, but remain a relevant and technically viable solution within their defined application envelope.