Haihao Group Manufactures Custom A105 and S275JR Flanges to Drawings for Spanish Customer
Not every flange required for an industrial piping project follows a standard catalogue configuration. Some orders involve specific drilling patterns, non-standard dimensions, and machining tolerances that must be followed directly from engineering drawings. Haihao Group recently completed a customized flange order for a customer in Spain, covering two sizes, DN250 and DN450, in S275JR and ASTM A105 materials.
The order involved custom flanges to drawing, with particular attention to dimensional accuracy, bolt-hole arrangements, and the different connection configurations specified for each size. Rather than applying one standard flange design to the entire batch, production was arranged according to the individual drawings supplied by the customer.
Two Flange Sizes, Two Different Material Specifications
The Spanish order included DN250 and DN450 flanges with different material and dimensional requirements. Each configuration was reviewed separately to ensure that the finished components followed the corresponding drawing.
The main product information is summarized below.
| Product | Nominal Size | Material | Drawing Requirements |
| Custom flange | DN250 | S275JR | ASME B16.5 600# configuration, according to drawing |
| Custom flange | DN450 (18″) | ASTM A105 | PN10, PN16 and ASME B16.5 150# drilling configurations |
For the DN250 components, the drawing specifies an outside diameter of 508 mm, an inside diameter of 273 mm, and a bolt circle diameter of 432 mm. Each flange has 16 bolt holes with a specified hole diameter of 35 mm. The drawing also defines the flange thickness and several additional machining dimensions.
The DN450 components have three drilling configurations. Although the nominal size remains unchanged, the outside diameter, bolt circle diameter, and bolt-hole dimensions vary according to the selected configuration.
This distinction is important when manufacturing custom flanges for piping systems with different connection requirements.
Custom A105 and S275JR industrial flanges manufactured by Haihao Group
DN250 S275JR Flanges: Detailed Dimensions and Machining Tolerances
The DN250 S275JR flanges are manufactured according to the customer’s detailed engineering drawing.
Key dimensions include:
Nominal diameter: DN250 (10 inches)
Material: S275JR
Drawing-specified flange configuration: ASME B16.5 600#
Outside diameter: 508 mm
Bolt circle diameter: 432 mm
Inside diameter: 273 mm
Number of bolt holes: 16
Bolt-hole diameter: 35 mm
Specified thickness: 27 mm
In addition to the main dimensions, the drawing identifies several smaller features, including chamfers, radii, and stepped machining sections.
These details cannot be overlooked during production. Even when the main diameter and thickness are correct, deviations in the bolt-hole positions or machined profiles may affect the component’s fit during installation.
For this reason, custom flanges to drawing require dimensional control beyond simply checking the nominal diameter.
DN450 ASTM A105 Flanges: Three Drilling Configurations
The DN450 (18-inch) A105 flanges have a different technical focus. The customer provided three drilling arrangements in the drawing:
| Drilling Configuration | Outside Diameter (OD) | Bolt Circle Diameter (OK) | Number of Holes | Hole Diameter |
| PN10 | 615 mm | 565 mm | 20 | 26 mm |
| PN16 | 640 mm | 585 mm | 20 | 30 mm |
| ASME B16.5 150# | 635 mm | 578 mm | 16 | 32 mm |
All dimensions are taken from the supplied customer drawing.
Why Drawing Review Is Important for Custom Flange Manufacturing
For standard flange orders, buyers can often specify a nominal size, pressure class, material, and manufacturing standard. Drawing-based orders require a more detailed review.
Several dimensions may be interconnected, and a small difference in one feature can affect the final assembly.
For the Spanish project, the manufacturing team needed to pay particular attention to:
1.Dimensional verification
Outside diameter, inside diameter, thickness, bolt circle, and hole diameter must correspond to the drawing.
2.Drilling accuracy
The number and position of bolt holes must match the specified connection arrangement. This is especially important for the DN450 flanges, which have three different drilling configurations.
3.Machined profiles
Chamfers, radii, grooves, and stepped sections are part of the finished component geometry and should not be treated as secondary details.
4.Material identification
S275JR and ASTM A105 are different material specifications. Material identification and traceability must be maintained separately throughout production.
5.Drawing tolerances
The permitted dimensional deviations must be considered during machining and final inspection rather than relying solely on nominal measurements.
These checks help ensure that the finished flanges correspond to the customer’s intended design.
Haihao Group’s Experience in Drawing-Based Flange Orders
Haihao Group manufactures industrial flanges and pipe fittings for customers in oil and gas, petrochemical, power generation, and other industrial sectors.
In addition to conventional standard products, the company handles orders involving customer-defined dimensions, special drilling arrangements, and customized machining profiles.
Looking for a Manufacturer for Custom Flanges?
Whether you need ASTM A105 flanges, S275JR flanges, or specially machined flange components, Haihao Group can review your drawings and discuss the manufacturing requirements.
If your project involves unusual dimensions, multiple drilling patterns, or specific machining tolerances, send us your technical drawings for evaluation.
Contact Haihao Group at sales@haihaogroup.com to discuss your flange requirements and request a quotation.