Hinged Non-Welded Centralizers for Primary Casing Cementing

Description

Goldenman Hinged Non-Welded Bow Spring Casing Centralizers maintain casing standoff during primary cementing operations in open-hole and cased-hole well sections.

Multiple heat-treated spring-steel bows contact the wellbore or previous casing string and generate restoring force that moves the casing away from the low side of the hole.

Improved casing centralization supports:

• More uniform annular clearance
• Improved drilling-fluid displacement
• Reduced mud-channel formation
• Improved cement coverage
• Reduced casing-to-formation contact
• Improved cement-sheath continuity
• Better zonal isolation
• Reduced remedial cementing risk

The hinged end collars allow the centralizer to be assembled directly around the casing at the rig site without passing the unit over the end of the casing joint.

The non-welded construction uses mechanically locked bow springs rather than welding the bows directly to the end collars. This allows individual bows, end collars and locking components to be inspected or replaced while avoiding weld heat-affected zones in the spring elements.

Standard sizes are available for casing and liner diameters from 3-1/2 to 30 inches, with different bow heights, blade quantities and compressed diameters for conventional, close-clearance, underreamed and washed-out wellbores.

Product Short Description

Goldenman Bow Spring Casing Centralizers use heat-treated spring-steel bows mechanically secured between two hinged steel end collars.

The bows compress while the casing passes through restrictions and then recover toward their original profile at the planned setting depth. This combination provides low starting and running forces together with the restoring force required to maintain casing standoff during cement placement.

The centralizer can be installed around the casing over a Stop Collar or positioned between two Stop Collars. Standard configurations are intended for vertical and deviated wells where casing rotation is not the primary operating requirement.

Each centralizer is selected according to casing OD, casing coupling OD, minimum restriction, nominal hole size, washed-out hole size, required standoff, centralizer placement and predicted running forces.

Product Highlights

• Hinged non-welded construction
• Casing sizes from 3-1/2 to 30 in
• Heat-treated spring-steel bows
• Mechanically locked bow ends
• Replaceable bows and end collars
• High restoring-force configurations
• Reduced starting-force configurations
• Reduced running-force configurations
• Multiple bow heights
• Multiple bow quantities
• Full circumferential casing support
• Suitable for open-hole and cased-hole applications
• Suitable for vertical and deviated wells
• Conventional and underreamed-hole configurations
• Washed-out-hole centralizer options
• Close-clearance configurations
• Installation without sliding over the casing end
• Compatible with hinged and slip-on Stop Collars
• Large annular flow area
• Minimal obstruction to cement flow
• Corrosion-resistant phosphate and powder-coated finish
• API Spec 10D performance testing available
• ISO 10427-1 test configurations available
• Starting-force testing
• Running-force testing
• Restoring-force testing
• Load-deflection reporting
• Standoff-performance reporting
• Batch and component traceability
• Custom bow and end-collar configurations

General Technical Specifications

Parameter	Available Configuration
Product	Hinged Non-Welded Bow Spring Casing Centralizer
Main application	Primary casing and liner cementing
Product size range	3-1/2–30 in
Construction	Hinged, mechanically assembled and non-welded
Bow material	Heat-treated spring steel
End-collar material	Carbon steel or alloy steel
Bow attachment	Locking tab or mechanically retained system
Bow profile	Single-crest or application-specific profile
Bow quantity	Size- and performance-dependent
End-collar type	Hinged latch-on
Installation	Over a Stop Collar or between Stop Collars
Hole applications	Open hole and cased hole
Well profiles	Vertical and deviated wells
Restriction service	Conventional and underreamed configurations
Surface treatment	Phosphate, paint or powder coating
Performance reference	API Spec 10D
International reference	ISO 10427-1
Placement reference	API RP 10D-2
Main performance data	Starting force, running force, restoring force and standoff
Supply condition	Assembled or component kit
Accessories	Stop Collars, locking pins and installation tools

Standard Casing Size Range

Goldenman supplies Bow Spring Centralizers for the following common casing and liner sizes:

Nominal Casing Size	Metric OD
3-1/2 in	88.9 mm
4 in	101.6 mm
4-1/2 in	114.3 mm
5 in	127.0 mm
5-1/2 in	139.7 mm
6-5/8 in	168.3 mm
7 in	177.8 mm
7-5/8 in	193.7 mm
8-5/8 in	219.1 mm
9-5/8 in	244.5 mm
10-3/4 in	273.1 mm
11-3/4 in	298.5 mm
13-3/8 in	339.7 mm
16 in	406.4 mm
18-5/8 in	473.1 mm
20 in	508.0 mm
24 in	609.6 mm
26 in	660.4 mm
30 in	762.0 mm

The final centralizer is not selected from casing OD alone.

Selection also requires:

• Casing coupling OD
• Casing nominal weight
• Minimum restriction ID
• Nominal open-hole diameter
• Maximum expected washed-out diameter
• Cased-hole ID
• Required compressed OD
• Required restoring force
• Required standoff
• Centralizer installation method

What Is a Bow Spring Casing Centralizer?

A Bow Spring Centralizer is installed around a casing or liner joint to keep the tubular away from the wellbore wall during casing running and cementing.

Each flexible bow behaves as a mechanical spring.

When the centralizer enters a restriction:

1. The bows compress toward the casing body.
2. The effective centralizer OD decreases.
3. The tool passes through the restriction.
4. The bows recover after leaving the restriction.
5. Restoring force pushes the casing toward the center of the hole.

The spring action allows one centralizer to operate across a defined range of hole diameters.

Why Casing Centralization Matters

A casing string lying against the low side of the wellbore creates a narrow annular gap.

Drilling fluid in this narrow section can become difficult to displace because of:

• Increased fluid resistance
• Gelled mud
• Filter cake
• Low local velocity
• Poor spacer contact
• Eccentric annular flow
• Restricted cement movement

This can result in:

• Mud channels
• Incomplete cement coverage
• Poor casing support
• Inadequate formation isolation
• Gas or fluid migration
• Sustained casing pressure
• Remedial squeeze cementing
• Reduced long-term well integrity

Bow Spring Centralizers improve annular geometry and support more even flow of spacer and cement around the casing.

Hinged Construction

The two end collars are divided into hinged sections.

During installation:

1. The collar is opened.
2. The centralizer is positioned around the casing.
3. The hinged collar is closed.
4. The locking pin or latch is installed.
5. The centralizer is positioned over or between Stop Collars.

The hinged construction provides:

• Rapid rig-site installation
• No requirement to slide the centralizer over the casing end
• Installation after casing accessories are already fitted
• Easier replacement of damaged components
• Compatibility with casing couplings and restricted assembly sequences
• Reduced casing-handling requirements

The hinge and latch are positioned to minimize interference while the casing is run.

Non-Welded Construction

The bow springs are mechanically attached to the end collars.

The non-welded design avoids welding directly across the heat-treated spring bow.

Advantages include:

• No bow-spring weld heat-affected zone
• Retained spring properties
• Replaceable bow elements
• Replaceable end collars
• Simplified field assembly
• Reduced risk of weld cracking at the bow connection
• Flexible production of different bow heights
• Efficient component stocking
• Cost-effective repair

Locking tabs or retaining elements transfer the operating load between the bows and end collars.

Bow Spring Design

Each bow is manufactured from formed spring steel.

The bow profile determines:

• Maximum expanded OD
• Minimum compressed OD
• Starting force
• Running force
• Restoring force
• Contact area
• Standoff capability
• Response after passing a restriction

Available bow configurations include:

• Standard bow
• Reduced-force bow
• High-restoring-force bow
• Low-profile bow
• High-profile bow
• Underreamed-hole bow
• Large-washout bow
• Wide-contact bow
• Narrow-contact bow

The bow height is matched to the casing and hole combination rather than using one universal bow for every hole diameter.

Heat-Treated Spring Steel

Bow springs require a controlled combination of strength, elasticity and fatigue resistance.

The manufacturing process can include:

• Spring-steel material verification
• Precision cutting
• Edge finishing
• Cold or hot forming
• Controlled heat treatment
• Quenching
• Tempering
• Hardness inspection
• Load-deflection testing
• Surface treatment

Correct heat treatment allows the bow to compress through restrictions and recover without excessive permanent deformation.

End Collars

The hinged end collars:

• Hold the bow springs in position
• Transfer axial movement to the centralizer
• Protect the bow ends
• Maintain circumferential bow spacing
• Support the hinge and locking system
• Fit the specified casing OD
• Work with the Stop Collar arrangement

End collars can include:

• Internal hinge
• External hinge
• Locking pin
• Latch plate
• Tab-lock system
• Reinforced edge
• Formed ribs
• Smooth bore
• Stop-collar clearance

The end-collar ID must match the casing body without excessive looseness or interference.

Bow Quantity

The number of bows is selected according to:

• Casing diameter
• Hole diameter
• Required restoring force
• Desired flow area
• Centralizer overall length
• Bow width
• Bow stiffness
• Expected side load

Increasing the number of bows can:

• Increase circumferential support
• Increase restoring force
• Improve load distribution
• Reduce unsupported casing areas

However, additional bows can also:

• Increase running force
• Increase contact area
• Reduce annular flow area
• Increase material cost

The optimum design balances standoff performance and casing-running resistance.

Starting Force

Starting force is associated with the force required to begin moving a new centralizer into a specified restriction or test hole.

Starting force is influenced by:

• Bow height
• Bow stiffness
• Bow quantity
• Compressed diameter
• Restriction diameter
• Surface finish
• Lubrication
• End-collar design
• Casing and hole alignment

Excessive starting force can increase:

• Hook-load requirements
• Casing-running resistance
• Risk of bow damage
• Risk of Stop Collar movement
• Difficulty passing casing shoes and restrictions

Goldenman offers reduced-force bow configurations for wells where running drag is a primary concern.

Running Force

Running force represents the resistance after the centralizer has entered the restriction and is moving through it.

Running force affects:

• Total casing-running drag
• Ability to reach planned depth
• Hook-load margin
• Stop Collar loading
• Casing reciprocation
• Running speed

A low starting force does not automatically guarantee a low running force.

Both values should be included in the performance report.

Restoring Force

Restoring force is the force generated by compressed bows as they push the casing away from the wellbore wall.

Higher restoring force supports:

• Improved casing standoff
• Reduced low-side contact
• More uniform annular clearance
• Better cement distribution
• Improved centralization in deviated intervals

Restoring force is affected by:

• Bow geometry
• Spring material
• Heat treatment
• Bow quantity
• Hole diameter
• Casing size
• Amount of bow compression
• Previous passage through restrictions

The complete load-deflection curve provides more useful engineering information than one isolated force value.

Standoff

Standoff describes the position of the casing within the annulus.

A fully centered casing has uniform clearance around its circumference.

A casing touching the wellbore wall has little or no clearance on one side.

The required standoff depends on:

• Hole geometry
• Well inclination
• Cementing objective
• Formation isolation requirements
• Fluid rheology
• Casing movement
• Available centralizer quantity
• Torque-and-drag limits

A minimum standard test result does not automatically represent the optimum standoff for every well.

Load-Deflection Curve

A Load-Deflection Curve shows how the centralizer responds as side load compresses the bows.

The curve helps engineers evaluate:

• Bow stiffness
• Restoring-force development
• Remaining standoff at a selected load
• Performance in different hole diameters
• Comparison between centralizer designs
• Response after passing through a restriction

Quotation and technical approval can include a model-specific Load-Deflection Curve.

Conventional-Hole Application

In a conventional application, the centralizer passes through a restriction that is approximately equal to the hole or casing ID at the final setting depth.

Typical examples include:

• Surface casing in a gauge hole
• Intermediate casing in a stable open hole
• Production casing in a cased-hole section
• Liner installation without a smaller upstream restriction

The centralizer is selected for the casing and final hole combination.

Underreamed-Hole Application

In an underreamed application, the centralizer must pass through a smaller restriction before expanding into a larger final hole.

Examples include:

• Passing through a previous casing string
• Passing through a liner-top restriction
• Passing through a casing shoe
• Entering an underreamed open-hole interval
• Passing through a window before entering a larger hole

Selection must include three dimensions:

• Casing OD
• Minimum restriction ID
• Final hole diameter

After compression through the restriction, the bow springs must retain sufficient restoring performance in the larger hole.

Washed-Out Hole Application

Washouts create hole diameters larger than nominal bit size.

A standard bow designed only for nominal hole diameter may provide insufficient contact and standoff inside a large washout.

Washed-out-hole configurations use:

• Increased bow height
• Modified spring geometry
• Increased free OD
• Additional bows
• Higher restoring-force design

The expected maximum hole diameter should be supplied from caliper or drilling data.

Open-Hole Applications

In open hole, the bows contact the formation.

The design must account for:

• Formation hardness
• Washouts
• Ledges
• Doglegs
• Hole enlargement
• Filter cake
• Cuttings beds
• Irregular borehole geometry
• Minimum restriction
• Maximum hole diameter

Bow Spring Centralizers adapt to moderate changes in open-hole diameter more effectively than fixed-gauge rigid centralizers.

Cased-Hole Applications

In cased hole, the centralizer contacts the ID of the previous casing string.

Cased-hole applications include:

• Liner cementing
• Tieback strings
• Inner casing strings
• Multi-stage casing programs
• Remedial cementing

Selection requires the previous casing:

• OD
• Nominal weight
• Wall thickness
• Drift ID
• Coupling ID
• Minimum restriction

Vertical Wells

In a vertical well, gravity produces relatively low lateral casing load.

Standard Bow Spring Centralizers can provide:

• High standoff
• Broad hole-size tolerance
• Low equipment cost
• Large cement-flow area
• Simple installation

Centralizer spacing can normally be wider than in high-angle intervals, subject to the cementing design.

Deviated Wells

As inclination increases, more casing weight acts against the low side of the hole.

The centralizer must provide sufficient restoring force to overcome a portion of this lateral load.

Selection considers:

• Inclination
• Dogleg severity
• Casing weight
• Centralizer spacing
• Hole diameter
• Friction coefficient
• Required standoff
• Running-force limit

High-restoring-force bows or closer centralizer spacing may be required.

Horizontal Wells

Traditional hinged non-welded Bow Spring Centralizers are principally suited to vertical and deviated sections where casing rotation is not required.

Long horizontal intervals can create:

• High lateral load
• High friction
• Bow flattening
• High running resistance
• Increased Stop Collar loading
• Difficulty maintaining standoff

For extended horizontal sections, alternative products can include:

• One-piece Bow Spring Centralizers
• Semi-rigid Centralizers
• Rigid Blade Centralizers
• Composite Centralizers
• Roller Centralizers
• Low-Friction Centralizers

The final selection should be based on torque-and-drag and centralizer-placement analysis.

Casing Rotation

Standard hinged non-welded centralizers are not the preferred choice when continuous casing rotation is required.

Rotation can cause:

• End-collar movement
• Stop Collar loading
• Bow and formation wear
• Hinge loading
• Irregular torque transfer

Applications requiring significant casing rotation should use a design specifically qualified for rotation, such as:

• Slip-on welded centralizer
• One-piece centralizer
• Rigid spiral centralizer
• Roller centralizer

Casing Reciprocation

The centralizer can move with the casing during controlled reciprocation when properly positioned with Stop Collars.

Reciprocation can improve:

• Mud displacement
• Spacer contact
• Cement distribution
• Filter-cake removal
• Annular velocity distribution

Stop Collars and centralizer end collars must be selected for the expected axial movement and force.

Stop Collar Installation

A Stop Collar controls the axial position of the centralizer.

Installation options include:

Centralizer Over One Stop Collar

The centralizer is assembled around a Stop Collar positioned beneath one end collar.

This arrangement allows limited axial movement while the Stop Collar pulls the centralizer with the casing.

Centralizer Between Two Stop Collars

One Stop Collar is installed above and one below the centralizer.

This arrangement provides controlled axial positioning and limits movement in both directions.

Centralizer Around a Casing Coupling

Selected designs can be positioned around or adjacent to a casing coupling when the centralizer and coupling dimensions are compatible.

The installation arrangement must be included in performance and running-force evaluation.

Stop Collar Types

Goldenman supplies:

• Hinged Set-Screw Stop Collars
• Hinged Spiral-Nail Stop Collars
• Slip-On Set-Screw Stop Collars
• Slip-On Spiral-Nail Stop Collars
• High-Holding-Force Stop Collars
• Non-Marking Stop Collars
• Integral Stop-Collar Rings
• Premium-Casing Stop Collars

Stop Collar selection considers:

• Casing OD
• Casing material
• Coating
• Required holding force
• Running direction
• Reciprocation
• Rotation
• Installation access
• Maximum permitted casing marking

Centralizer Placement

The number and spacing of centralizers are calculated from:

• Casing OD
• Casing nominal weight
• Hole diameter
• Hole inclination
• Dogleg severity
• Centralizer load-deflection data
• Required standoff
• Open-hole geometry
• Cased-hole restrictions
• Stop Collar configuration
• Friction coefficient
• Casing movement plan

Common placement areas include:

• Around the casing shoe
• Above and below Float Equipment
• Across productive formations
• Across isolation intervals
• Around stage cementing equipment
• Around liner hangers
• Across weak or fractured formations
• Across gas-bearing intervals
• Across high-dogleg sections

Centralizers should not be spaced using a fixed “one per joint” rule without reviewing well geometry and required standoff.

Centralization Near Float Equipment

Centralizers are commonly positioned near:

• Float Shoe
• Float Collar
• Shoe Track
• Bottom Cementing Plug landing interval

This supports:

• Centralized shoe placement
• Improved initial annular cement distribution
• Reduced shoe-side channeling
• Controlled clearance around float equipment
• Improved drill-out alignment

The first centralizer position must still allow safe passage through the wellbore and previous casing shoe.

Centralization Across Critical Zones

Closer centralizer spacing can be used across:

• Hydrocarbon-bearing formations
• Water-bearing formations
• Gas zones
• Lost-circulation intervals
• Weak formations
• Pressure-transition zones
• Stage-cementing intervals
• Casing-overlap sections

The purpose is to improve cement coverage where isolation performance has the greatest operational or well-integrity impact.

Bow Spring vs Rigid Centralizer

Selection Factor	Bow Spring Centralizer	Rigid Blade Centralizer
External diameter	Compressible	Fixed
Hole-size adaptability	High	Limited to fixed geometry
Restoring action	Spring force	Geometric standoff
Tight restriction passage	Better	Requires sufficient clearance
Washed-out-hole performance	Available with high bows	Limited by blade OD
Running friction	Bow and design dependent	Contact and material dependent
Horizontal side-load capacity	Limited by bow compression	High
Casing rotation	Design dependent	Often more suitable
Main application	Vertical and deviated wells	Deviated and horizontal wells

Hinged vs Slip-On Centralizer

Hinged Centralizer	Slip-On Centralizer
Opens around casing	Slides over casing end
Fast installation at rig site	Installed before end accessories prevent access
Can be installed after coupling makeup	Requires a clear casing end
Uses hinge and locking pin	Uses continuous end collar
Easy component replacement	Greater end-collar continuity
Suitable for non-rotating applications	Selected designs are more suitable for rotation

Non-Welded vs Welded Bow Spring Centralizer

Non-Welded Design	Welded Design
Bows mechanically locked to collars	Bows welded to end collars
No weld heat-affected zone in bow attachment	Rigid bow-to-collar connection
Replaceable components	Normally supplied as one finished assembly
Flexible field assembly	Greater structural rigidity
Suitable for conventional cementing	Suitable for high-load and selected rotating applications
Often hinged	Hinged or slip-on

Cement-Flow Area

The spaces between the bows allow drilling fluid, spacer and cement to flow around the centralizer.

A suitable design balances:

• Bow quantity
• Restoring force
• Flow area
• Debris bypass
• ECD
• Solids tolerance
• Cement velocity
• Mud-removal efficiency

Excessively wide solid components can restrict annular flow and increase local pressure loss.

Equivalent Circulating Density

Centralizers occupy part of the annular flow area.

The cementing program should consider the pressure loss across:

• Centralizers
• Stop Collars
• Float Equipment
• Stage Tools
• Casing Couplings
• Narrow annular sections

Open bow geometry limits flow restriction compared with large solid-body accessories.

Material Selection

Bow Material

Bow material requires:

• High elastic recovery
• Fatigue resistance
• Controlled hardness
• Resistance to permanent set
• Forming capability
• Repeatable load-deflection behavior

Spring-steel grade and heat treatment are controlled by the qualified product design.

End-Collar Material

End collars are manufactured from:

• Carbon steel
• Low-alloy steel
• Galvanized steel
• Coated steel
• Corrosion-resistant project material

End collars provide structural support but are not pressure-containing components.

Locking Components

Locking pins, tabs and retainers require:

• Impact resistance
• Vibration resistance
• Secure engagement
• Corrosion protection
• Easy rig-site installation

Surface Protection

Available surface treatments include:

• Iron phosphate
• Zinc phosphate
• Black paint
• Epoxy coating
• Polyester powder coating
• Zinc plating
• Galvanizing
• Project-specific corrosion-resistant coating

Surface protection reduces atmospheric corrosion during transportation and storage.

The selected coating must remain compatible with installation, downhole fluids and cementing temperatures.

Standard-Service Configuration

Standard Bow Spring Centralizers are used with:

• Water-Based Mud
• Oil-Based Mud
• Synthetic-Based Mud
• Completion brine
• Spacers
• Cement slurry
• Wash fluids

The design must account for temperature, corrosion exposure and fluid chemistry during the planned well operation.

High-Temperature Configuration

High-temperature service can require:

• Temperature-resistant coating
• Stable spring heat treatment
• High-temperature locking components
• Material-property verification
• Extended thermal-exposure testing

The maximum temperature should be included in the quotation.

Sour-Service Applications

The centralizer is not a pressure-containing component, but sour-service projects can still require:

• Controlled material hardness
• H₂S-compatible coatings
• Material traceability
• Corrosion-resistant fasteners
• Project-specific material approval

Performance Testing

Centralizer performance evaluation can include:

• Starting-force testing
• Running-force testing
• Restoring-force testing
• Load-deflection testing
• Standoff determination
• Restriction-passage testing
• Post-restriction performance testing
• Stop Collar holding-force testing
• Bow permanent-set inspection
• Component-retention testing

Test reports must identify the exact:

• Centralizer design
• Part number
• Casing OD
• Hole ID
• Minimum restriction
• Installation arrangement
• Stop Collar or coupling configuration
• Test orientation
• Lubrication condition

API Spec 10D Positioning

API Spec 10D provides testing, performance and marking requirements for Bow Spring Casing Centralizers used in oil and gas well construction.

It applies to Bow Spring Casing Centralizers and does not automatically cover:

• Rigid Blade Centralizers
• Roller Centralizers
• Cement Baskets
• Wireline Centralizers
• Gravel-Pack Centralizers
• Inner-String Centralizers

Product descriptions should state:

Tested in accordance with API Spec 10D

or:

Performance validated to API Spec 10D requirements

The statement must be supported by the corresponding model and size test report.

ISO 10427-1

ISO 10427-1 provides the international Bow Spring Casing Centralizer standard.

Project documentation can specify:

• API Spec 10D
• ISO 10427-1
• Both API and ISO references
• Customer-specific supplementary testing

Centralizer Placement and Stop Collar Testing

Centralizer placement is calculated using the load-deflection performance of the selected centralizer and the well geometry.

Stop Collar testing evaluates the holding force of the installed Stop Collar under the specified test arrangement.

The Stop Collar must withstand the axial load generated when:

• The centralizer enters a restriction
• The casing is run downward
• The casing is pulled upward
• The casing is reciprocated
• The centralizer encounters a ledge
• The bows compress through a casing shoe

Installation Procedure

1. Confirm casing OD and nominal weight.
2. Confirm the centralizer part number.
3. Confirm the hole and restriction dimensions.
4. Inspect the bows for shipping damage.
5. Inspect the end collars and hinge.
6. Inspect the locking pin or latch.
7. Install the required Stop Collar.
8. Open both hinged end collars.
9. Position the centralizer around the casing.
10. Close the collars.
11. Install and secure the locking components.
12. Confirm that all bows are correctly retained.
13. Confirm that the centralizer moves as designed.
14. Verify the axial position.
15. Record the installed joint and depth.

Installation Over a Stop Collar

When installed over a Stop Collar:

• Confirm that the Stop Collar fits inside the centralizer end collar.
• Confirm adequate axial clearance.
• Confirm that the centralizer cannot pass over the Stop Collar.
• Verify the Stop Collar holding force.
• Position the assembly according to the casing tally.

Installation Between Stop Collars

When installed between two Stop Collars:

• Set the lower Stop Collar first.
• Place the centralizer around the casing.
• Set the upper Stop Collar.
• Maintain the specified axial movement allowance.
• Confirm that neither collar interferes with bow compression.

Pre-Run Inspection

Before casing running, inspect:

• Bow cracks
• Permanent bow deformation
• Missing bows
• Damaged locking tabs
• Loose hinges
• Missing locking pins
• End-collar deformation
• Coating damage
• Incorrect size
• Incorrect bow height
• Incorrect Stop Collar
• Incorrect installation orientation

A centralizer with damaged or permanently flattened bows should not be installed.

Handling and Storage

Centralizers should be:

• Stored in a dry covered area
• Separated by size and part number
• Protected from heavy loads
• Kept away from corrosive chemicals
• Protected from uncontrolled impact
• Transported in crates or secured pallets
• Stored without flattening the bow profile

Do not use Bow Spring Centralizers as lifting points or supports for casing bundles.

Common Failure Modes

Centralizer Does Not Pass a Restriction

Possible causes include:

• Incorrect compressed OD
• Hole restriction smaller than specified
• Damaged bow
• Incorrect bow height
• Debris accumulation
• Casing coupling interference
• Misaligned hinge
• Excessive running speed

Excessive Running Force

Possible causes include:

• Centralizer selected for the wrong restriction
• Excessive bow stiffness
• Too many bows
• Inadequate lubrication
• Rough cased-hole ID
• Ledge or dogleg
• Incorrect centralizer orientation
• Inaccurate hole-size information

Insufficient Standoff

Possible causes include:

• Hole washout larger than expected
• Bow height too low
• Restoring force too low
• Excessive centralizer spacing
• Permanent bow set
• High lateral casing load
• Incorrect placement
• Damaged bows after restriction passage

Bow Breakage

Possible causes include:

• Incorrect spring material
• Improper heat treatment
• Severe impact
• Excessive restriction
• Repeated high-cycle compression
• Corrosion
• Manufacturing defect
• Improper installation

Bow Becomes Permanently Flattened

Possible causes include:

• Restriction below qualified size
• Excessive side load
• Long static compression
• Incorrect bow heat treatment
• Extended horizontal loading
• Repeated passage through severe restrictions

End Collar Opens Downhole

Possible causes include:

• Missing locking pin
• Incorrect latch engagement
• Hinge damage
• Excessive rotational loading
• Improper installation
• Impact with a restriction

Stop Collar Slips

Possible causes include:

• Incorrect Stop Collar size
• Insufficient screw torque
• Incorrect nail installation
• Casing coating
• Excessive starting force
• Casing reciprocation
• Inadequate holding-force rating

Manufacturing Process

Goldenman Bow Spring Centralizer manufacturing includes:

1. Spring-steel material verification
2. End-collar material verification
3. Component batch assignment
4. Bow blank cutting
5. Edge finishing
6. Bow forming
7. Bow heat treatment
8. Bow hardness inspection
9. End-collar forming
10. Hinge manufacturing
11. Locking-tab production
12. Surface preparation
13. Phosphate treatment
14. Painting or powder coating
15. Mechanical assembly
16. Bow-retention inspection
17. Expanded-OD inspection
18. Compressed-OD inspection
19. Dimensional inspection
20. Functional compression testing
21. Performance testing according to the inspection scope
22. Product marking
23. Final visual inspection
24. Export packaging

Quality Control

Quality control includes:

• Raw-material certificate verification
• Spring-steel composition review
• Bow thickness inspection
• Bow width inspection
• Bow-height inspection
• Heat-treatment verification
• Bow hardness testing
• End-collar ID inspection
• End-collar width inspection
• Hinge inspection
• Locking-system inspection
• Expanded-OD measurement
• Compressed-OD measurement
• Overall-length inspection
• Bow quantity verification
• Assembly inspection
• Coating inspection
• Compression-and-recovery testing
• Batch traceability
• Final visual inspection

Product Marking

Each centralizer or package can be marked with:

• Goldenman identification
• Product type
• Part number
• Casing size
• Nominal hole size
• Minimum restriction where applicable
• Bow configuration
• Batch number
• Manufacturing date
• Performance-standard reference
• Installation direction where required

Product Documentation

Available documentation includes:

• Certificate of Conformity
• Product datasheet
• Centralizer dimensional drawing
• Casing and hole-size chart
• Material certificate
• Spring-steel material report
• Heat-treatment record
• Hardness report
• Dimensional inspection report
• Expanded-OD report
• Compressed-OD report
• Starting-force test report
• Running-force test report
• Restoring-force test report
• Load-deflection curve
• Standoff-performance report
• Restriction-passage test report
• Stop Collar holding-force report
• Batch traceability list
• Installation instructions
• Centralizer-placement data
• Packing list
• Third-party inspection report

Packaging

Packaging options include:

• Component kits
• Fully assembled centralizers
• Steel-strapped bundles
• Wooden crates
• Export pallets
• Moisture-resistant wrapping
• Size-separated packaging
• Individual product labels

Hinged non-welded designs can be supplied as compact component kits to reduce transportation and storage volume.

Frequently Asked Questions

What product is shown on this page?

This page covers Hinged Non-Welded Bow Spring Casing Centralizers for primary casing and liner cementing.

What sizes are available?

Standard casing sizes range from 3-1/2 to 30 inches.

The final centralizer also requires the hole size and minimum restriction.

Is “3 4/2 inch” a casing size?

No.

The correct minimum size on the original product range is 3-1/2 inches.

What does non-welded mean?

The bow springs are mechanically retained in the end collars rather than welded directly to them.

What is the advantage of a hinged centralizer?

It can be opened and installed around the casing without sliding the centralizer over the casing end.

Can the centralizer be installed over a Stop Collar?

Yes.

A common arrangement places the centralizer over a qualified Stop Collar so that it moves with the casing.

Can it be installed between two Stop Collars?

Yes.

Two Stop Collars can limit centralizer movement in both axial directions.

What is starting force?

Starting force is associated with the force required to begin moving the centralizer into a specified restriction.

What is running force?

Running force is the resistance while the centralizer moves through the restriction after initial entry.

What is restoring force?

Restoring force is the spring force that moves the casing away from the wellbore wall after the bows are compressed.

What information is needed to evaluate standoff?

Required information includes:

• Casing size and weight
• Hole diameter
• Minimum restriction
• Well inclination
• Dogleg severity
• Centralizer spacing
• Load-deflection data

Can one centralizer be used in different hole sizes?

A qualified bow configuration can cover a specified hole-size range.

The approved minimum restriction and maximum hole diameter must be defined.

Can the centralizer pass through a smaller casing shoe?

An underreamed-hole configuration can be designed to pass through a specified restriction and recover in a larger hole.

Is it suitable for washed-out holes?

High-profile bows are available for larger and washed-out hole diameters.

Is it suitable for horizontal wells?

Traditional hinged non-welded centralizers are best suited to vertical and deviated wells with controlled lateral loading.

Extended horizontal intervals often require one-piece, semi-rigid, rigid or low-friction centralizers.

Can casing be rotated with this centralizer?

Standard non-welded hinged models are intended primarily for non-rotating casing strings.

A rotation-qualified centralizer should be selected where substantial casing rotation is planned.

Does API Spec 10D determine centralizer spacing?

API Spec 10D addresses Bow Spring Centralizer testing, performance and marking.

Centralizer placement calculations and Stop Collar testing are addressed separately under API RP 10D-2.

Is the product API Monogrammed?

Bow Spring Centralizers should be described as tested or performance-validated to API Spec 10D when supported by the applicable test report.

The API Monogram should not be applied to these products.

What test reports are available?

Available reports include:

• Starting-force test
• Running-force test
• Restoring-force test
• Load-deflection curve
• Standoff-performance report
• Restriction-passage test
• Stop Collar holding-force test

Are custom bow heights available?

Yes.

Bow height, width, thickness, quantity and free OD can be configured for the casing, restriction and hole-size combination.

Are Stop Collars supplied?

Yes.

Hinged, slip-on, set-screw and spiral-nail Stop Collars can be supplied with the centralizers.

Information Required for Quotation

Please provide:

• Casing OD
• Casing nominal weight
• Casing coupling OD
• Casing grade
• Open-hole or cased-hole application
• Nominal hole diameter
• Maximum expected hole diameter
• Minimum restriction ID
• Previous casing ID
• Casing-shoe ID
• Well depth
• Well inclination
• Maximum dogleg severity
• Target cementing interval
• Required standoff
• Required centralizer spacing
• Casing running or reciprocating plan
• Casing rotation requirement
• Maximum acceptable starting force
• Maximum acceptable running force
• Minimum restoring-force requirement
• Standard or underreamed application
• Bow quantity
• Bow height
• Stop Collar type
• Stop Collar holding-force requirement
• Maximum operating temperature
• Drilling-fluid type
• Cement-slurry type
• Sour-service requirement
• API Spec 10D testing requirement
• ISO 10427-1 requirement
• API RP 10D-2 placement data
• Third-party inspection
• Documentation requirements
• Required quantity
• Destination country
• Delivery schedule

Request a Technical Quotation

Goldenman supplies Hinged Non-Welded Bow Spring Casing Centralizers for primary casing and liner cementing in open-hole and cased-hole well sections.

The product range covers:

• Casing sizes from 3-1/2 to 30 in
• Conventional and underreamed-hole configurations
• Standard and high-restoring-force bows
• Reduced starting- and running-force designs
• Multiple bow heights and bow quantities
• Hinged mechanically assembled end collars
• Matched Stop Collars
• API Spec 10D performance testing
• ISO 10427-1 test configurations
• Centralizer-placement and Stop Collar test data

Complete orders can be supplied with material traceability, dimensional reports, starting-force data, running-force data, restoring-force curves, standoff-performance results and installation instructions.

Email: info@goldenman.com