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Hebei Haihao Group Huadian High Pressure Pipe Fittings Co., Ltd.Hebei Haihao Group Huadian High Pressure Pipe Fittings Co., Ltd.Pressure Pipe Fittings · Flanges · Factory Direct

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Buyer guide

How to Source Medium & Low Pressure Flanges: A Procurement Guide for EPC Buyers

Learn key criteria for selecting a reliable flange manufacturer for medium and low pressure applications, including standards, inspection documentation, and RFQ best practices.

June 28, 2026·4 min read·Hebei Haihao Group
海浩法兰管件:中低压管件法兰的选择生产商
海浩法兰管件:中低压管件法兰的选择生产商

On this page

  • Introduction
  • Key Standards to Confirm
  • Material Selection for Medium/Low Pressure Flanges
  • Required Inspection Documents
  • RFQ Checklist
  • Quality Risks in Medium/Low Pressure Flanges
  • What to Send Before Quotation
  • Why Choose Hebei Haihao Group?

Introduction

Medium and low pressure pipe flanges are critical components in industrial piping systems. For EPC procurement engineers, selecting the right manufacturer directly impacts project safety, cost, and schedule. This guide provides practical criteria for evaluating flange suppliers, with a focus on medium and low pressure applications.

Key Standards to Confirm

Before issuing an RFQ, ensure the manufacturer can produce flanges to the following common standards:

  • ASME B16.5: For flanges and flanged fittings, covering pressure-temperature ratings up to Class 600.
  • ASME B16.47: For large diameter flanges (Series A and B).
  • DIN 2501 (or EN 1092-1): For metric flanges used in Europe.
  • JIS B2220: For Japanese standard flanges.

Also verify that materials meet ASTM specifications such as A105 (carbon steel), A182 (alloy and stainless steel), or A350 (low temperature carbon steel).

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Material Selection for Medium/Low Pressure Flanges

Material choice affects corrosion resistance, weldability, and cost. For typical water, oil, gas, or steam services:

ServiceRecommended MaterialRemarks
General purpose, moderate temperatureCarbon steel ASTM A105Most economical; avoid in sour service unless treated
Corrosive or high temperatureStainless 304/316 (ASTM A182)Better durability; higher cost
Low temperature (below -20°C)A350 LF2Impact tested for brittle fracture resistance

Always confirm that material certificates state heat number and chemical composition.

Required Inspection Documents

A reliable manufacturer should provide complete documentation for traceability and compliance:

  • Material Test Certificates (MTC) as per EN 10204 3.1 or 3.2
  • Dimensional inspection reports
  • Visual and surface defect inspection (ASTM A788, ASME B16.5)
  • If applicable: hardness tests, PMI (Positive Material Identification) reports
  • Pressure test certificates if required by client spec
  • Third-party inspection reports (e.g., from BV, SGS, Lloyd’s)

RFQ Checklist

When preparing an RFQ for medium/low pressure flanges, include at least the following details:

  • Quantity and size range (nominal pipe size, schedule, facing type)
  • Pressure class (e.g., 150#, 300# up to 600#)
  • Material grade (carbon steel, stainless, alloy)
  • Standard (ASME, DIN, JIS, etc.)
  • Facing type (raised face, flat face, ring joint)
  • Surface finish requirements (e.g., 125-250 microinch for raised face)
  • Marking requirements (material, pressure class, manufacturer logo)
  • Packaging and shipment (wooden crates, pallets, or as per project)
  • Inspection requirements (third-party or client witness)

Quality Risks in Medium/Low Pressure Flanges

Although medium and low pressure flanges are not subject to extreme conditions, common quality issues include:

  • Porosity and inclusions due to poor forging control.
  • Dimensional deviations in bolt circle diameter, flange thickness, or hub length, causing gasket misalignment.
  • Improper heat treatment leading to inadequate mechanical properties.
  • Surface defects like scratches or pitting that can accelerate corrosion.

Requesting a pre-production sample and conducting a dimensional inspection on arrival can mitigate these risks.

What to Send Before Quotation

To get an accurate quotation from a flange manufacturer, provide:

  • Full technical specification (standard, material, class, size)
  • Quantity (total pieces or annual demand)
  • Required delivery date
  • Any special requirements (e.g., painting, zinc plating, specific coatings)
  • Preferred payment terms (L/C, T/T) and delivery terms (FOB, CIF)

Consider sending a request for a quality audit if the supplier is new to you.

Why Choose Hebei Haihao Group?

Hebei Haihao Group has extensive experience in manufacturing forged flanges, pipe fittings, and bends for medium and low pressure systems. Our products comply with major international standards and are supported by complete documentation. We serve EPC contractors and industrial buyers globally with competitive lead times and transparent inspection processes.

To discuss your project requirements or request a quote, contact our sales team with your RFQ details.

Need a quote for the products mentioned in this article?

Submit your specs and our pressure piping team will respond within one business day.

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About the publisher

Hebei Haihao Group Huadian High Pressure Pipe Fittings Co., Ltd.

Since 1982

Established in 1982, Hebei Haihao Group Huadian High Pressure Pipe Fittings Co., Ltd. manufactures flanges and pipe fittings in Mengcun County, Cangzhou City, Hebei Province.

40+ years in pressure piping · ~10,000 t / year output · ISO 9001 · ABS Type Approval

Edited by the Hebei Haihao engineering desk

www.haihaohuadian.com

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On this page

  • Introduction
  • Key Standards to Confirm
  • Material Selection for Medium/Low Pressure Flanges
  • Required Inspection Documents
  • RFQ Checklist
  • Quality Risks in Medium/Low Pressure Flanges
  • What to Send Before Quotation
  • Why Choose Hebei Haihao Group?

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Products covered in this article

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锻制法兰产品图Flange
Forged Flanges and Nonstandard Forgings

Carbon Steel, Stainless Steel, Alloy Steel

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Forged Flange - 法兰 (1)Flange
Forged Flange

ASTM A105 / A182 / A350; carbon, alloy and stainless steel

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Socket Weld Flange - 承插法兰 (1)Flange
Socket Weld Flange

ASTM A105 / A182 F11/F22/F304/F316; GB/T carbon, alloy, stainless steel

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