Head profile · FHA

Flat heads, covers and flat tank bottoms (FHA)

Flat plates with a formed straight flange for welding, supplied to drawing with the edge preparation and openings your assembly needs.

Profile and application

A flat head is a plate closure with a straight flange or other edge form for joining to a shell. The outside diameter, flange length, material, thickness and weld preparation are confirmed from the drawing. Openings and lifting points can be included where the design allows.

Outside diameter: Ø200–3000 mm
Wall thickness: 2–20 mm
Reference form: GB/T 25198 · customer drawing
Typical use: Tank bottoms, covers and low-pressure closures

Flat closures are common on low-pressure tanks, covers and equipment where a dished profile is not required. The project design remains responsible for pressure adequacy; our quotation covers the geometry, material, forming and inspection scope specified on the approved drawing.

FHA cross-section. Final height, straight flange and edge form follow the approved drawing.

Specification at a glance

Code	Profile	Reference form	Outside diameter	Wall thickness	Typical use
FHA	Flat head or tank bottom (FHA)	GB/T 25198 · customer drawing	Ø200–3000 mm	2–20 mm	Tank bottoms, covers and low-pressure closures

The published diameter is the equipment range, not a record that every size has already run. A new diameter or profile starts with a tooling check and, where required, a dimensioned first article for approval. See the full head-type comparison.

Common applications

Tank bottoms

Flat or flanged bottoms for low-pressure storage and process tanks.

Covers and closures

Removable or welded covers where a dished profile is not needed.

General fabrication

Flat end plates with openings and weld preparation to drawing.

Materials and finishes

Family	Grades	Typical use
Carbon steel	Q235B, Q345B, SA-36, SA-414G (Q345R on request)	Storage tanks, receivers, general fabrication
Stainless steel	201, 304/2B, 304/BA, 30408 (304L and 316L on request)	Solar and hot-water cylinders, food, pharma, chemical
Aluminium	5083-O and other 5xxx grades	LNG vehicle cylinders, Dewar flasks, cryogenic service
Finishes	2B, BA, pickled, polished — necking zone Ra ≤ 0.4 µm	Where appearance or cleanliness matters

Grades outside the listed families can be reviewed on request. The material certificate supplied with the batch is tied to the heat number.

What to send for a quotation

Finished drawing, size list or sample photograph
Outside diameter, overall height and straight flange
Material grade and required surface finish
Openings, necks, bosses or lifting features with positions
Quantity, inspection requirement and delivery port

If some dimensions are still open, send the application and current sketch. We will list what has to be fixed before a price or tooling decision can be made.

Documentation and inspection

Dimensional report with the agreed measured features
Material certificate tied to the heat number
Radiographic, ultrasonic or magnetic particle testing on request
Third-party inspection welcomed for the agreed scope

Send the RFQ

Questions buyers ask first

Can the flat head have a formed straight flange?

Yes. The flange height, inside or outside fit, edge profile and weld preparation are made to drawing. State whether the head fits inside the shell, outside the shell or butts to it.

Can you cut openings into a flat head?

Yes. Openings can be cut or formed to the drawing, including pipe connections, bosses and access openings. Provide the opening schedule with positions and any reinforcement requirements.

Can you calculate the pressure rating for me?

The design pressure rating must come from the responsible vessel designer or engineer against the applicable code. We manufacture the specified geometry and material and confirm the dimensional and inspection basis before order.

What thickness can be supplied?

The nominal range for FHA work is 2–20 mm, subject to diameter, material, edge form and equipment availability. Send the finished drawing so the exact plate and forming route can be confirmed.

Compare other head profiles

2:1 elliptical head (EHA)

The standard vessel profile with crown height D/4. Pressed in carbon steel, stainless steel and aluminium.

Torispherical dished head (THA)

Crown and knuckle radii to your drawing, from thin stainless end caps to heavier low-pressure tank heads.

Hemispherical head (HHA)

Half-sphere profile with crown height D/2 for high-pressure, LNG and cryogenic equipment.

Conical head or transition (CHA)

Conical bottoms and transitions to your apex angle, knuckle radius and straight flange, with or without openings.

Request a quote

Send the flat-head drawing with flange detail, plate grade, openings and inspection scope.

Open the RFQ form [email protected]

Quotes usually go out within one working day. Drawings stay confidential.