Mounting Holes/Bolts: Component Specs, Materials & Applications

Component Specifications

Definition

Mounting holes are precisely machined apertures in valve housings that accommodate bolts for secure attachment to pipelines, manifolds, or supporting structures. These components ensure proper alignment, prevent leakage, and maintain structural integrity under operational pressures and vibrations. The bolt-hole interface creates a clamped joint that distributes mechanical loads evenly across the flange surface.

Working Principle

Mounting holes provide geometric constraints for bolt placement, while bolts apply tensile preload through torque application. This creates friction at flange interfaces that resists shear forces and maintains gasket compression. The combined system transforms bolt tension into clamping force that seals the valve housing against pressure differentials and mechanical stresses.

Materials

Holes: Machined directly into valve housing material (typically ASTM A216 WCB cast steel or ASTM A351 CF8M stainless). Bolts: ASTM A193 B7 alloy steel or ASTM A320 L7 for high-temperature applications, with ISO 898-1 Class 8.8 or 10.9 strength grades. Corrosion protection: Zinc plating, hot-dip galvanizing, or Xylan coatings.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Surface Finish	Ra 3.2 μm maximum for sealing surfaces
Flange Thickness	12-50mm depending on pressure rating
Preload Accuracy	±15% of target torque
Bolt Thread Pitch	ISO 262 coarse or fine series
Hole Diameter Tolerance	H7/g6 per ISO 286
Bolt Torque Specification	30-200 Nm per ASME PCC-1

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ASME B16.5, DIN 2501, API 6D, EN 1092-1

Parent Products

This component is used in the following industrial products

Valve Housing/Body

The structural enclosure that contains and supports the internal components of a valve within an air distribution system.

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Engineering Analysis

Risks & Mitigation

Stress corrosion cracking in chloride environments
Galvanic corrosion between dissimilar metals
Bolt loosening from vibration
Flange warpage from uneven torque application
Thread stripping from over-torquing

FMEA Triads

Trigger: Incorrect bolt torque sequence
Failure: Uneven flange loading leading to gasket blowout
Mitigation: Implement cross-pattern torque sequence per ASME PCC-1, use calibrated torque wrenches, and verify with ultrasonic bolt tension measurement

Trigger: Corrosion between steel bolts and stainless housing
Failure: Seizure making maintenance disassembly impossible
Mitigation: Apply anti-seize compounds with nickel or copper bases, specify isolation washers, or use compatible material combinations

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Hole position within ±0.5mm of true position, perpendicularity within 0.1mm per 100mm flange thickness

Test Method

Dye penetrant inspection for crack detection, ultrasonic thickness measurement, bolt load verification using strain gauges or hydraulic tensioners

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Mounting Holes/Bolts

Manufacturer profiles associated with Mounting Holes/Bolts.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

What determines the number of mounting holes in a valve housing?

The quantity follows ASME B16.5 standards based on flange size and pressure class. Typically 4-16 holes arranged in bolt circle patterns to ensure even gasket compression and prevent flange distortion.

How does bolt preload affect valve performance?

Proper preload maintains gasket sealing integrity. Insufficient preload causes leakage under pressure cycling, while excessive preload can distort the flange or cause bolt fatigue failure. Torque values are calculated based on bolt grade and lubrication conditions.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Mounting Holes/Bolts