SERRATED FLANGES

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

1. Industry Context & System Relevance

Role of Serrated Flanges in Pressure Systems

Serrated flange joints represent one of the most critical potential leakage points. While pipe, fittings, and valves are typically pressure-rated components with defined wall thickness, the flange joint relies on a combination of mechanical preload and surface interaction to achieve sealing.

Serrated Flanges are used in:

• Refineries & Petrochemical Plants
• Upstream and Midstream Oil & Gas Pipelines
• Power Generation Units (Thermal, Nuclear, Combined Cycle)
• LNG Liquefaction and Regasification Terminals
• Chemical Processing Units
• Offshore Platforms and Subsea Modules

These environments impose:

• High internal pressures
• Thermal cycling
• Corrosive media exposure
• Dynamic loading and vibration

Under such conditions, flange face finish becomes a deterministic factor in joint reliability.

Function in Bolted Flange Joints

A bolted flange joint consists of:

• Two mating flanges
• A gasket
• Bolting system (studs, nuts, washers)

The sealing is achieved by:

1. Applying bolt preload
2. Compressing the gasket between flange faces
3. Generating sufficient contact stress to prevent fluid escape

Serrated flange faces directly influence:

• Gasket seating behavior
• Frictional resistance to gasket movement
• Load distribution across sealing surface

Why Serrated Flange Faces Are Used

Smooth flange faces provide limited frictional interaction with gasket materials, particularly under high-pressure service. This may result in:

• Gasket slippage
• Uneven compression
• Loss of sealing stress
• Blowout under pressure fluctuations

Serrated Flanges introduce controlled surface roughness, which:

• Improves mechanical interlocking between gasket and flange
• Enhances sealing reliability
• Increases resistance to gasket extrusion and blowout
• Stabilizes gasket under cyclic loads

Smooth Face vs Serrated Face Sealing Performance

Parameter	Smooth Face Flange	Serrated Flange
Gasket Grip	Low	High
Friction Coefficient	Lower	Controlled & Higher
Sealing Reliability	Moderate	High
Blowout Resistance	Limited	Improved
Gasket Stability	Prone to movement	Mechanically restrained
Load Distribution	Less uniform	Enhanced distribution

Engineering Interpretation:

Serrations create micro-contact points that penetrate slightly into the gasket surface, producing a more stable and predictable sealing interface.

Importance in High-Pressure and High-Temperature Joints

In elevated service conditions:

• Gaskets experience creep relaxation
• Bolts lose preload due to thermal expansion differences
• Flanges may undergo rotation and deformation

Serrated surfaces help compensate by:

• Maintaining contact stress through mechanical anchoring
• Reducing dependency on purely elastic gasket behavior
• Supporting long-term sealing under load relaxation

2. Technical Definition of Serrated Flanges

Engineering Definition

Serrated Flanges are pressure-retaining flanges with machined surface finishes consisting of controlled concentric or spiral grooves on the sealing face, designed to enhance gasket sealing performance under bolted preload conditions.

Structural Characteristics

A serrated flange includes:

• Flange body (forged or rolled)
• Bolt holes (precision drilled)
• Sealing face (RF, FF, or RTJ)
• Machined serration profile on contact surface

Types of Serrated Flange Faces

Raised Face (RF) Serrated Finish

• Most commonly used configuration
• Serrations applied on a raised portion of flange face
• Standard height per ASME:
  • Class 150–300: 1.6 mm (1/16″)
  • Class 400 and above: 6.4 mm (1/4″)

Function:

• Concentrates gasket load within defined sealing zone
• Improves gasket compression efficiency

Flat Face (FF) Serrated Finish

• Entire flange face is in contact
• Serrations applied across full face

Application:

• Low-pressure systems
• Cast iron or non-metallic flange connections
• Situations where bending stress must be minimized

Ring Type Joint (RTJ) vs Serrated RF

Feature	Serrated RF	RTJ
Sealing Method	Gasket compression	Metal-to-metal ring
Surface Finish	Serrated	Smooth precision groove
Pressure Range	Medium to High	High to Very High
Reusability	Limited (depends on gasket)	Ring replaced each use
Installation Complexity	Moderate	High

Engineering Note:
RTJ flanges rely on plastic deformation of a metal ring, whereas serrated RF flanges depend on surface roughness-controlled gasket interaction.

Stock Finish vs Phonographic Serration

Stock Finish (Standard Serration)

• Spiral serrations generated via lathe machining
• Roughness range:
  • 125 to 250 AARH (3.2 to 6.3 µm Ra)
• Continuous spiral groove from center outward

Phonographic Serration (Spiral Finish)

• Similar to record grooves
• Produced using controlled feed rate on lathe

Characteristics:

• Provides continuous sealing path
• Preferred for soft gasket materials

Concentric Serrations

• Independent circular grooves
• No continuous spiral path

Application:

• Used where leakage paths must be minimized
• Often preferred for critical sealing applications

3. Engineering & Sealing Principle

Gasket Compression Mechanics

When bolts are tightened:

1. Tensile force is induced in bolts
2. Compressive force is transferred to gasket
3. Gasket deforms to fill flange surface irregularities

The effectiveness of sealing depends on:

• Achieved gasket stress
• Surface interaction between flange and gasket

Serration Penetration Mechanism

Serrated flanges function by:

• Creating localized high-pressure contact points
• Allowing serrations to slightly embed into gasket surface
• Increasing frictional resistance against lateral movement

This produces:

• Improved sealing under low bolt preload
• Resistance to blowout under internal pressure

Load Distribution Across Flange Face

In a smooth face:

• Load distribution is less controlled
• Micro-gaps may exist

In a serrated face:

• Load is distributed through multiple contact ridges
• Stress concentration enhances sealing

Result:
More uniform and predictable gasket compression.

Micro-Sealing Theory

Sealing occurs at microscopic level:

• Gasket material flows into serration valleys
• Peaks penetrate gasket surface
• Micro voids are eliminated

This creates:

• Multiple sealing barriers
• Reduced leakage pathways

Surface Roughness (Ra) vs Sealing Performance

Surface Roughness	Effect
Too Smooth (< 1.6 µm)	Poor gasket grip
Optimal (3.2–6.3 µm)	Balanced sealing & durability
Too Rough (> 6.3 µm)	Gasket damage risk

Engineering Control:
Maintaining controlled roughness is essential to avoid:

• Gasket tearing
• Insufficient sealing stress
• Excessive embedment

Spiral vs Concentric Serration Behavior

Feature	Spiral Serration	Concentric Serration
Leakage Path	Continuous path possible	Interrupted paths
Gasket Compatibility	Soft gaskets	Semi-metallic gaskets
Manufacturing Ease	Easier	More controlled machining
Sealing Performance	Standard	Enhanced in critical services

Blowout Resistance Improvement

Blowout occurs when:

• Internal pressure exceeds gasket retention force

Serrations improve resistance by:

• Increasing frictional retention
• Anchoring gasket material
• Reducing lateral displacement

Bolt Preload vs Gasket Stress Relationship

The sealing mechanism depends on:

• Bolt preload → generates gasket seating stress
• Internal pressure → tends to separate flange

To maintain seal:

Gasket Stress ≥ Internal Pressure-Induced Separation Force

Serrated flanges help maintain this relationship by:

• Enhancing effective contact stress
• Reducing dependence on high bolt loads

Leakage Prevention Through Controlled Surface Finish

Leakage occurs when:

• Micro-channels exist between flange and gasket

Controlled serration ensures:

• Channels are interrupted
• Gasket fills voids effectively
• Fluid path is blocked

Engineering Interpretation

Serrated flanges are not merely surface-finished components; they are:

• Precision-engineered sealing interfaces
• Designed to control:
  • Contact stress
  • Frictional behavior
  • Gasket deformation

Their effectiveness depends on:

• Surface finish accuracy
• Bolt preload control
• Gasket compatibility

4. Applicable Standards (ASTM / ASME / DIN / ISO)

Standards Framework for Serrated Flanges

The design, manufacture, inspection, and application of Serrated Flanges are governed by a combination of dimensional, material, and surface finish standards. These standards ensure interchangeability, pressure integrity, and sealing performance across global EPC projects.

ASME Standards

ASME B16.5

Applies to:

• NPS ½” to 24″
• Pressure Classes: 150 to 2500

Defines:

• Flange dimensions (OD, ID, thickness)
• Bolt circle and hole patterns
• Raised Face (RF) geometry
• Pressure-temperature ratings

Relevance to Serrated Flanges:

• Governs flange geometry on which serrations are applied
• Ensures compatibility with gaskets and bolting systems
• Specifies raised face height affecting gasket compression

ASME B16.47 – Large Diameter Flanges

Applies to:

• NPS 26″ to 60″
• Series A (MSS SP-44) and Series B (API 605)

Defines:

• Large diameter flange dimensions
• Bolt patterns and load distribution
• Structural rigidity requirements

Engineering Relevance:

Large-diameter Serrated Flanges require:

• Controlled serration uniformity across wider surfaces
• Consideration of flange rotation under bolt load

MSS Standard

MSS SP-6 – Standard Finishes for Contact Faces

Critical standard for serration control.

Defines:

• Surface finish types
• Roughness limits
• Machining requirements

Specified Stock Finish:

• 125–250 AARH (Arithmetic Average Roughness Height)
• Equivalent to approximately 3.2–6.3 µm Ra

Importance:

• Directly influences gasket seating performance
• Standardizes sealing interface across manufacturers

ASTM Material Standards

ASTM standards define:

• Chemical composition
• Mechanical properties
• Heat treatment conditions

Relevant material standards include:

• ASTM A105 (carbon steel forgings)
• ASTM A350 LF2 (low-temperature carbon steel)
• ASTM A182 (alloy and stainless steels)

DIN EN Standards

DIN EN 1092-1

Defines:

• Metric flange dimensions
• PN pressure ratings (PN10 to PN400)
• Face types including RF and FF

Relevance:

• Used in European EPC projects
• Requires compatibility with EN gasket standards

ISO Standards

ISO flange standards align with:

• Global dimensional compatibility
• International procurement specifications

Examples:

• ISO 7005 (metal flanges)
• ISO surface finish equivalence to MSS SP-6

Standards Mapping to Engineering Parameters

Parameter	Governing Standard
Dimensions	ASME B16.5 / B16.47 / DIN EN 1092
Pressure Rating	ASME B16.5 / EN 1092
Surface Finish	MSS SP-6
Material	ASTM Standards
Inspection	ASTM / ASME / EN

5. Material & Grade Options

Material Selection Philosophy

Material selection for Serrated Flanges is based on:

• Operating pressure and temperature
• Corrosive environment
• Mechanical loading conditions
• Compatibility with mating components

Carbon Steel Grades

ASTM A105

• Standard forging material for ambient and elevated temperatures
• Suitable for oil & gas, refineries, and general industrial piping

ASTM A350 LF2

• Designed for low-temperature service
• Improved notch toughness
• Used in cryogenic and sub-zero applications

Stainless Steel Grades

ASTM A182 F304

• Austenitic stainless steel
• Good corrosion resistance
• Suitable for chemical and water systems

ASTM A182 F316

• Molybdenum-bearing stainless steel
• Enhanced resistance to chlorides and acids
• Preferred for marine and chemical environments

Alloy Steel Grades

ASTM A182 F11

• Chromium-molybdenum alloy
• Suitable for moderate high-temperature service

ASTM A182 F22

• Higher chromium content
• Used in high-pressure, high-temperature systems such as power plants

Duplex & Super Duplex Stainless Steel

• Dual-phase microstructure
• High strength and corrosion resistance
• Resistant to stress corrosion cracking

Applications:

• Offshore platforms
• Seawater systems
• Aggressive chemical environments

Material Comparison Table

Grade	Yield Strength (MPa)	Tensile Strength (MPa)	Temperature Range	Corrosion Resistance	Typical Application
ASTM A105	~250	485–620	-29°C to 425°C	Moderate	Oil & gas piping
ASTM A350 LF2	~250	485–620	-46°C to 345°C	Moderate	Low-temperature service
A182 F304	~205	515–720	-196°C to 870°C	Good	Chemical plants
A182 F316	~205	515–720	-196°C to 870°C	High	Marine, chemical
A182 F11	~275	485–620	Up to 540°C	Moderate	Power plants
A182 F22	~415	585–760	Up to 600°C	Moderate	High-pressure systems
Duplex SS	~450	620–880	-50°C to 300°C	Very High	Offshore, seawater

Engineering Considerations in Material Selection

• Higher strength materials reduce flange thickness requirements
• Corrosion-resistant alloys extend service life
• Thermal expansion compatibility must be maintained with piping

6. Heat Treatment Information

Purpose of Heat Treatment

Heat treatment ensures:

• Uniform microstructure
• Mechanical property consistency
• Stress relief after forging and machining

Normalizing

Process:

• Heating above critical temperature
• Air cooling

Effect:

• Grain refinement
• Improved toughness
• Uniform structure

Used for:

• Carbon steel flanges (A105)

Quenching and Tempering (Q&T)

Process:

1. Rapid cooling (quenching)
2. Controlled reheating (tempering)

Effect:

• Increased strength
• Improved hardness
• Controlled ductility

Used for:

• Alloy steels (F11, F22)

Solution Annealing

Used for:

• Stainless steels

Process:

• Heating to high temperature
• Rapid cooling

Effect:

• Dissolves carbides
• Restores corrosion resistance

Stress Relieving

Purpose:

• Remove residual stresses from machining and forging

Effect:

• Dimensional stability
• Reduced distortion during service

Mechanical Property Stabilization

Heat treatment ensures:

• Consistent yield strength
• Predictable tensile behavior
• Resistance to brittle fracture

Hardness Ranges

Typical hardness:

• Carbon steel: 120–187 HB
• Alloy steel: 150–220 HB
• Stainless steel: 140–200 HB

Charpy Impact Testing

Conducted for:

• Low-temperature applications

Measures:

• Material toughness
• Resistance to brittle fracture

Standards:

• ASTM A370

7. Manufacturing Process

Raw Material Inspection

• Chemical composition verification
• Ultrasonic testing for internal defects
• Mill test certificate validation

Forging / Ring Rolling

• Open-die forging or rolled rings
• Grain flow aligned with flange geometry

Importance:

• Enhances mechanical strength
• Reduces internal defects

CNC Machining

Operations include:

• Turning of OD and ID
• Facing operations
• Bore machining

Control Parameters:

• Dimensional tolerances
• Surface finish

Serration Machining (Critical Step)

Performed using:

• Lathe-based facing tools

Controlled parameters:

• Feed rate
• Tool geometry
• Depth of cut

Objective:

• Achieve required roughness (Ra)
• Maintain uniform serration pitch

Drilling

• Bolt holes drilled using CNC machines
• Ensures alignment with bolt circle

Heat Treatment

• Applied as per material specification
• Controlled furnace conditions

Surface Finishing

• Removal of machining marks
• Anti-corrosion coating (if specified)

Final Inspection

• Dimensional verification
• Surface roughness measurement
• Visual inspection

Marking & Traceability

Includes:

• Material grade
• Heat number
• Pressure class
• Manufacturer identification

Ensures:

• Full traceability for EPC projects

Surface Finish – Critical Engineering Requirement

Stock Finish Specification

Standard serrated finish:

• 125–250 AARH
• 3.2–6.3 µm Ra

Generated via:

• Continuous spiral machining

Types of Serrated Finishes

Spiral Serrated Finish

• Continuous groove
• Common for RF flanges

Concentric Serrations

• Discrete circular grooves
• Used for critical sealing

Effect on Gasket Seating

Surface Condition	Effect
Smooth	Poor grip
Controlled Serration	Optimal sealing
Excessively Rough	Gasket damage

Acceptable Roughness Ranges

• Soft gaskets: 3.2–6.3 µm Ra
• Metallic gaskets: lower Ra preferred
• Graphite gaskets: moderate serration required

Inspection Methods

Surface roughness measured using:

• Stylus profilometer
• Optical surface measurement tools

Parameters checked:

• Ra (average roughness)
• Rz (peak-to-valley height)

Engineering Control Requirements

• Uniform serration across entire face
• No radial scratches or discontinuities
• Controlled pitch and depth

8. Flange Dimension Tables (ASME Reference Data)

The following tables represent typical dimensional logic for Serrated Flanges in accordance with ASME B16.5. Values shown are indicative for engineering reference; project-specific drawings govern final supply.

Class 150 – Raised Face Serrated Flanges

NPS (in)	OD (mm)	ID (mm)	Thickness (mm)	Bolt Circle (mm)	No. of Bolts	Bolt Size
1″	108	27	14	79	4	M14
2″	152	53	16	121	4	M16
4″	229	102	19	191	8	M16
6″	279	154	21	241	8	M20
8″	343	203	24	298	8	M20
10″	406	254	26	362	12	M20

Class 300 – Raised Face Serrated Flanges

NPS (in)	OD (mm)	ID (mm)	Thickness (mm)	Bolt Circle (mm)	No. of Bolts	Bolt Size
1″	124	27	18	89	4	M16
2″	165	53	20	127	8	M16
4″	254	102	24	200	8	M20
6″	318	154	28	270	12	M20
8″	381	203	32	330	12	M24
10″	445	254	35	387	16	M24

Dimensional Engineering Interpretation

• Increase in pressure class results in:
  • Higher flange thickness
  • Increased bolt quantity and diameter
  • Larger bolt circle diameter
• This ensures:
  • Higher bolt preload capacity
  • Reduced flange rotation
  • Improved gasket stress retention

9. Pressure Rating vs Temperature

Pressure rating depends on material group and temperature.

ASME Pressure-Temperature Relationship (Carbon Steel)

Temperature (°C)	Class 150 (bar)	Class 300 (bar)	Class 600 (bar)	Class 900 (bar)
38°C	19.6	51.1	102.1	153.2
100°C	17.7	46.0	92.0	138.0
200°C	15.2	39.5	79.0	118.5
300°C	13.3	34.6	69.2	103.8
400°C	11.8	30.7	61.4	92.1

Engineering Considerations

• As temperature increases:
  • Allowable stress decreases
  • Pressure rating reduces
• Serrated flange performance depends on:
  • Maintaining gasket stress despite thermal expansion
  • Controlling bolt relaxation

Torque Chart

Torque values are indicative for achieving required preload using standard bolting materials.

Torque Values for ASTM A193 B7 Stud Bolts

Bolt Size	Torque (Nm) – Dry	Torque (Nm) – Lubricated
M16	210	160
M20	410	310
M24	710	530
M27	1050	790
M30	1450	1100
M36	2500	1850

Torque Values for Property Class 8.8

Bolt Size	Torque (Nm) – Dry	Torque (Nm) – Lubricated
M16	190	140
M20	370	280
M24	640	480
M30	1300	980

Engineering Interpretation

• Lubrication reduces friction → lower torque required
• Torque must be controlled to:
  • Prevent under-tightening (leakage)
  • Avoid over-tightening (bolt yielding, flange distortion)

10. Preload & Gasket Stress Calculation Guide

Bolt Load Equation

   

Where:

• ( F ) = Bolt preload (N)
• ( T ) = Applied torque (Nm)
• ( K ) = Torque coefficient (typically 0.18–0.25)
• ( d ) = Nominal bolt diameter (m)

Gasket Seating Stress

   

Where:

• ( \sigma_g ) = Gasket stress (MPa)
• ( F ) = Total bolt load
• ( A_g ) = Effective gasket area

Flange Separation Force

   

Where:

• ( F_s ) = Separation force
• ( P ) = Internal pressure
• ( A_i ) = Internal pipe area

Sample Calculation

Given:

• Torque = 500 Nm
• Bolt diameter = 20 mm (0.02 m)
• K = 0.2

Bolt Load:

   

If:

• Gasket area = 0.01 m²

Gasket Stress:

   

Engineering Interpretation

For sealing integrity:

• Gasket seating stress must exceed:
  • Minimum seating stress
  • Internal pressure separation effect

Serrated flanges assist by:

• Increasing effective sealing through surface interaction
• Reducing required preload for same sealing performance

Mechanical Properties Table

Material	Yield Strength (MPa)	Tensile Strength (MPa)	Hardness (HB)	Impact (J)
A105	250	485–620	120–187	≥27
LF2	250	485–620	120–187	≥40
F304	205	515–720	140–200	≥60
F316	205	515–720	140–200	≥60
F22	415	585–760	150–220	≥27

Corrosion Resistance Table

Material	Marine	Acidic	Hydrocarbon	Humidity
A105	Low	Low	Good	Moderate
LF2	Low	Low	Good	Moderate
F304	Moderate	Moderate	Good	High
F316	High	High	Excellent	High
Duplex SS	Very High	High	Excellent	Very High

Inspection & Quality Control

Surface Roughness Measurement

• Equipment: Profilometer
• Parameters:
  • Ra (average roughness)
  • Rz (peak-to-valley height)

Critical for Serrated Flanges:

• Ensures compliance with MSS SP-6
• Directly impacts gasket sealing

Positive Material Identification (PMI)

• Confirms alloy composition
• Required for:
  • Stainless steels
  • Alloy steels

Non-Destructive Testing (NDT)

Ultrasonic Testing (UT)

• Detects internal flaws

Magnetic Particle Inspection (MPI)

• Surface and near-surface defects

Dye Penetrant Inspection (DPI)

• Surface crack detection

Dimensional Inspection

Verification of:

• OD, ID, thickness
• Bolt hole alignment
• Raised face height
• Serration uniformity

Hardness Testing

• Confirms heat treatment effectiveness
• Ensures compliance with material standards

Hydrostatic Testing (Assembly Level)

• Conducted on assembled flange joints
• Validates sealing performance under pressure

Third-Party Inspection

Common agencies:

• TPI as per EPC requirement

Inspection includes:

• Witness of tests
• Document verification
• Dimensional validation

Certification

• EN 10204 3.1 (Mill Test Certificate)
• EN 10204 3.2 (Third-party verified certificate)

Traceability Control

Each flange is traceable through:

• Heat number
• Batch number
• Material certification

11. Industries Served

Oil & Gas (Upstream, Midstream, Downstream)

Serrated Flanges are deployed extensively across:

• Wellhead facilities
• Gathering and transmission pipelines
• Refinery process units

Engineering Requirements:

• Resistance to pressure fluctuations
• Compatibility with hydrocarbon service
• Reliability under cyclic loading

Application Areas:

• Pump and compressor connections
• Heat exchangers
• Pressure vessels
• Pipeline tie-ins

Refineries & Petrochemical Plants

Refining and petrochemical operations involve:

• High temperatures
• Reactive chemical environments
• Continuous process duty

Role of Serrated Flanges:

• Maintain gasket sealing under thermal expansion
• Provide stability for soft and semi-metallic gaskets
• Support maintenance cycles without excessive flange wear

Power Generation

Used in:

• Thermal power plants
• Combined cycle plants
• Nuclear auxiliary systems

Service Conditions:

• High-temperature steam
• High-pressure cycles
• Thermal fatigue conditions

Engineering Need:

• Controlled flange rotation
• Stable gasket stress over extended cycles

LNG Terminals

Applications include:

• Cryogenic pipelines
• Liquefaction and regasification systems

Material Considerations:

• Low-temperature toughness (ASTM A350 LF2, stainless steel)
• Resistance to brittle fracture

Serration Role:

• Maintains sealing under contraction and expansion cycles

Chemical Processing Plants

Exposure to:

• Acids
• Alkalis
• Solvents

Engineering Focus:

• Corrosion-resistant materials
• Controlled surface finish for gasket compatibility

Offshore Platforms

Operating conditions:

• Saltwater exposure
• High humidity
• Mechanical vibration

Requirement:

• Corrosion-resistant alloys (F316, Duplex)
• Reliable sealing under dynamic loading

Cross-Industry Engineering Relevance

Across all industries, Serrated Flanges are selected where:

• Gasket sealing reliability is critical
• Maintenance intervals must be optimized
• Leakage risk must be minimized

12. Export Capability & Global Supply

Supply Regions

Super Industries supplies Serrated Flanges to:

• United States (ASME compliance)
• European Union (EN / PED compliance)
• Middle East (project-specific specifications)
• Southeast Asia (mixed ASME/EN requirements)

Export Packaging

Packaging is designed to protect:

• Serrated sealing surfaces
• Machined dimensions
• Corrosion-sensitive materials

Methods:

• Wooden crates (ISPM-15 compliant)
• Anti-rust coating or VCI wrapping
• Protective flange face covers

Documentation Package

Supplied documentation includes:

• Mill Test Certificates (EN 10204 3.1 / 3.2)
• Dimensional inspection reports
• Surface roughness reports (Ra values)
• Heat treatment charts
• NDT reports (UT / MPI / DPI)
• PMI reports (where applicable)

Project Logistics

• Batch traceability maintained throughout supply chain
• Marking aligned with EPC tagging systems
• Packaging aligned with project-specific handling procedures

Compliance Support

• Alignment with project specifications
• Review of client drawings and datasheets
• Documentation for third-party inspection clearance

Procurement & Installation Guidelines

Pre-Installation Inspection

Before installation of Serrated Flanges, verify:

• Surface finish (no damage to serrations)
• Flatness and parallelism
• Cleanliness of flange face
• Correct material grade and pressure class

Do Not Install If:

• Serrations are flattened or damaged
• Foreign particles are present
• Surface corrosion is visible

Gasket Selection

Gasket must be compatible with:

• Flange face finish
• Operating pressure and temperature
• Process fluid

Typical Options:

• Spiral wound gaskets
• Graphite gaskets
• PTFE gaskets

Bolt Tightening Sequence (Star Pattern)

Bolting must follow a cross-pattern (star sequence):

1. Initial snug tightening
2. Sequential tightening in star pattern
3. Multiple passes to achieve uniform load

Objective:

• Uniform gasket compression
• Minimized flange distortion

Torque Application Stages

Typical tightening stages:

• Stage 1: 30% of final torque
• Stage 2: 60% of final torque
• Stage 3: 100% of final torque
• Final pass: Circular pass for uniformity

Re-Torque Procedure

After initial operation:

• Allow system to stabilize
• Re-check bolt torque

Purpose:

• Compensate for gasket creep relaxation
• Restore required preload

Flange Face Alignment

Ensure:

• Parallel alignment of mating flanges
• No angular misalignment
• Uniform gasket seating

Misalignment can lead to:

• Uneven gasket compression
• Leakage
• Flange rotation

Storage & Handling

Store Serrated Flanges:

• In dry, covered environment
• Away from moisture and contaminants

Handling precautions:

• Protect serrated surfaces with covers
• Avoid stacking without separation
• Prevent mechanical damage

Custom Engineering Capabilities

Super Industries provides project-specific solutions for Serrated Flanges, including:

Non-Standard Sizes

• Large diameter flanges beyond standard ASME ranges
• Custom thickness and bore dimensions

Custom Serration Profiles

• Modified pitch and depth
• Concentric or spiral configurations
• Project-specific surface roughness requirements

Special Facing Requirements

• Controlled Ra values outside standard ranges
• Hybrid face finishes for specific gasket types

Tight Machining Tolerances

• Enhanced flatness control
• Precision bolt hole alignment
• Reduced surface waviness

Coating & Corrosion Protection

• Anti-corrosion coatings
• Oil or varnish protection
• Specialized coatings for offshore applications

13. Procurement Evaluation Perspective (EPC Focus)

From an EPC procurement and technical evaluation standpoint, qualification of a Serrated Flange manufacturer depends on:

Surface Finish Control Capability

• Ability to maintain MSS SP-6 roughness range
• Measured and documented Ra values

Manufacturing Consistency

• Repeatability of serration profiles
• Dimensional compliance across batches

Material Traceability

• Full traceability from raw material to finished product
• Verified chemical and mechanical properties

Inspection Infrastructure

• Availability of NDT
• Surface roughness measurement systems
• Third-party inspection readiness

Documentation Compliance

• Complete and verifiable documentation
• Alignment with project specifications

Engineering Conclusion

Serrated Flanges function as precision-engineered sealing interfaces within bolted flange joints. Their performance is determined not only by dimensional compliance but by:

• Controlled surface roughness
• Gasket interaction behavior
• Bolt preload accuracy
• Material integrity

In high-pressure and high-temperature systems, the serrated face provides:

• Enhanced gasket retention
• Improved sealing reliability
• Resistance to leakage under cyclic and thermal loading

For EPC applications, the suitability of Serrated Flanges is established through:

• Compliance with ASME, ASTM, and MSS standards
• Verified manufacturing processes
• Documented inspection and testing
• Proven capability to maintain surface finish tolerances

Final Engineering Statement

A properly manufactured and installed serrated flange joint achieves sealing through the combined interaction of controlled surface finish, gasket deformation, and bolt-induced preload, ensuring system integrity across demanding industrial applications.