Bulb Flat

What is a bulb flat profile?

Bulb Flat is a structural profile with a flat bottom and a small "spherical protrusion" on one side. This unique cross-sectional form not only improves the bending resistance, but also has excellent welding adaptability and compact structure. It is often used as ribs and stiffeners in many fields such as shipbuilding, offshore platforms, steel structures, and wind power supports.

Chalco can provide bulb profiles in a variety of materials including:

Chalco bulb flat product parameters

Standard size range: width 60–430 mm, thickness 4–20 mm

Length options: 6m/9m/12m, or cut to length as required

Tolerance control: thickness ±0.3mm, width ±0.5mm (depending on the material)

Common specifications (applicable to carbon steel bulb flat profiles): HP80×6, HP100×8, HP160×9, HP220×10, etc.

Processing options: Support secondary processing services such as punching, grooving, bending, and angle processing

Certification standards: in compliance with ISO, DNV, ABS, CCS, ASTM and other international classification societies and industry quality system requirements

Aluminum bulb flat

Known for their light weight, high strength, strong corrosion resistance and good machinability; ideal for modern shipbuilding, rail transportation and high-end equipment manufacturing. Supply elbow pipe fittings.

Recommended size: width 60–430mm, thickness 4–20mm, length can be customized.

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• Lightweight and high strength: meets the dual needs of industrial lightweight and structural strength.
• Excellent corrosion resistance: suitable for long-term exposure environments such as marine, construction, and electrical.
• Excellent processability: supports deep processing such as laser cutting, CNC finishing, bending, punching, anodizing, etc.

Typical applications:

It is suitable for high-performance fields such as lightweight ship components, wind power structures, rail transit skeletons, aerospace and electronic frame systems.

Technical parameters: If you need customized solutions and data sheets for aluminum alloy bulb flat profiles, please contact the sales team. [Quick Mailbox]

Carbon steel bulb flat

Chalco carbon steel bulb profiles have excellent strength and welding performance, and are reliable supporting materials for various heavy structures, hull frames and bridge projects.

Recommended size: HP80×6, HP100×8, HP160×9, HP220×10, etc.

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Certification and specification standards: in accordance with ASTM A36, ASTM A131, EN10025, GB712 and other standards

Flat profiles provided by Chalco cover standard marine steels such as Grade A, AH36, DH36, etc., all of which can be certified by IACS (International Association of Classification Societies) members such as DNV, ABS, CCS, LR, BV, etc., to ensure their compliance in ship structures and marine engineering.

Features:

• Rich standardized specifications: Supports standard marine specifications from HP80×6 to HP430×20
• Good welding and load-bearing performance: suitable for welding frames and heavy structural parts
• Support post-processing technology: can provide processing services such as hole opening, chamfering, spraying, coating, etc.

Typical applications:

key parts such as hull frames, bridge beam webs, offshore platform stiffeners, and large industrial steel structures.

Technical parameters: If you need customized solutions and data sheets for carbon steel bulb flat profiles, please contact the sales team. [Quick Mailbox]

Stainless steel bulb flat

Chalco stainless steel bulb flat profiles are widely used in harsh environments such as petrochemical, power, medical and high-end manufacturing due to their excellent corrosion resistance, high cleanliness and structural stability.

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Certification and specification standards: Conforms to ASTM A240, EN10088, GB/T 3280 and other standards, and can provide SGS, ISO 9001, food grade testing and other certifications according to industry needs.

Features:

• Excellent corrosion and high temperature resistance
• Supports various surface treatments such as brushing, mirror, pickling, electrolysis, etc.
• Compatible with precision welding and cutting processes

Typical applications:

• Special parts of ships (such as corrosion-resistant areas, clean cabins, high-end yacht structures, etc.)
• Petrochemical equipment structural parts
• Power and energy transmission structure
• Medical equipment brackets and clean environment materials

Technical parameters: If you need customized solutions and data sheets for stainless steel bulb flat profiles, please contact the sales team. Quick Quote

Chalco bulb flat technical advantages and processing and manufacturing capabilities

Product and material advantages

• Full coverage of materials: We provide spherical flat profiles made of various materials such as aluminum alloy, carbon steel, stainless steel, etc. to meet the needs of multiple scenarios such as structural strength, corrosion resistance, and lightweight.
• Superior performance: high strength-to-weight ratio, excellent bending and corrosion resistance.
• Surface optimization design: The rounded corner design eliminates the need for additional polishing, which can improve coating adhesion and extend service life.
• Complete certification: The products comply with ASTM, EN, GB and other standards, and support DNV, ABS, LR, CCS, BV and other international classification society certifications.

Quality assurance and service system

• Traceability system: Each bulb flat profile has a unique identity code, which enables full traceability from billet to finished product.
• Standardized production process: Implement ISO9001, ISO14001 and other quality and environmental management systems.
• Processing accuracy guarantee: ensure edge flatness and angle accuracy through fine grinding, adapt to automatic welding and rapid assembly requirements.
• Flexible production scheduling mechanism: supports customers' project-based production scheduling and delivery needs to ensure project progress.
• Fast delivery and flexible batch: support small batch customization and large batch rolling delivery, and samples can be produced within 7 days.

Manufacturing and processing capabilities

Chalco has a complete production line from raw material preparation to deep processing and surface treatment to meet high standard delivery needs:

• CNC precision machining capabilities: support CNC milling, turning and other multi-axis finishing of complex structural parts;
• Large-size bending and forming capabilities: The maximum bending length can reach 24 feet, suitable for large aluminum plates and special-shaped sections;
• Complete cutting capabilities: including laser, water jet, band saw, circular saw, etc., suitable for various materials and thicknesses;
• Compatible with various welding processes: master TIG/MIG, spot welding, butt welding, suitable for a variety of metals;
• Rich surface treatment processes: anodizing, electrophoresis, hot-dip galvanizing, sandblasting, polishing to meet the needs of corrosion resistance and aesthetics;
• High-precision dimensional control: tolerance control is as fine as ±0.02mm;

Precision equipment support

• CNC processing equipment: VF-10, Viper, YCM, Multicam and other brand equipment, supporting high-speed, ultra-long-stroke precision milling and turning.
• Laser and water jet cutting platform: 96"×300" laser platform (12kw), maximum 10 ' ×26 ' water jet platform, with high cutting accuracy and no thermal deformation.
• Sawing and shearing equipment: Kasto, Cosen, Hem series equipment, capable of cutting materials up to 25 inches thick or 24 inches in diameter.
• Forming and processing equipment: The maximum tonnage of the hydraulic bending machine is 165 tons, supporting the bending of 24 -foot large -size workpieces.
• Welding and surface treatment equipment: equipped with MIG/TIG welding stations, polishing machines, roller deburring and other auxiliary finishing equipment.

Chalco bulb flat cooperation in marine field

Chalco has extensive experience in marine profile cooperation and has long provided high-quality bulb profile products to global shipyards, offshore equipment companies and maritime supporting enterprises. We can not only supply carbon steel bulb profiles that meet international certifications such as DNV, ABS, and CCS, but also meet the customized needs of aluminum alloy profiles under the trend of lightweight hulls. Quick Quote

• Wide coverage of international certification: supports DNV, ABS, LR, CCS, BV and other classification society certifications, and is compatible with mainstream material standards such as Grade A, AH36, 5083-O, etc.
• Customized delivery according to project: Recommended specifications based on hull drawings, support 7-day proofing and 6-12m fixed-length delivery.
• One-stop processing service: integrating drilling, welding, cutting, spraying and other supporting processes to reduce customer coordination costs.
• Strong supporting capabilities: can be designed in coordination with keel plates, rib plates, steel sections and other structural parts, and supplied in batches.
• Rich experience in international engineering: Participated in many export shipbuilding and offshore engineering projects and familiar with technical specifications of various countries.
• Stable and guaranteed delivery: mature supply chain and sufficient inventory ensure on-time delivery of large orders.

Chalco bulb flat for shipbuilding

Material type: carbon steel, aluminum alloy Project Features: Used for core structures such as main keel and hull frame, in compliance with ABS/DNV and other international classification society certifications; supports 6m/9m/12m fixed-length supply.

Cooperation value: Provide a full range of materials such as Grade A / AH36 / 5083-O; assist shipyards in quickly docking drawings.

Chalco bulb flat for bridge structure

Material Type: Carbon Steel

Project Features: Integrated solutions for bending, punching and spraying of key components such as bridge decks and beam webs.

Cooperation value: Chalco provides one-stop supply service of panels + processing, which reduces the amount of cutting and processing at the construction end and saves construction time.

Offshore platform stiffeners

Material Type: Carbon Steel

Project Features: Suitable for stiffening parts of complex structures

Cooperation value: high strength, supports grooving and groove customization, and can quickly respond to short-cycle requirements of offshore projects.

Wind tower internal support

Material type: aluminum alloy

Project features: Used for tower internal wiring pipe support, ladder bracket, etc.

Cooperation value: Support 6061 / 6082 alloy extrusion + surface treatment, reduce the total weight of the structure and extend the life.

Ports and offshore facilities

Material Type: stainless steel

Project Features: Suitable for high-corrosion marine environments

Cooperation value: 316L stainless steel is used, which is resistant to salt spray and corrosion; it is equipped with clean welding and mirror treatment.

We understand the unique needs of different industries for bulb flat profiles and have the ability to tailor solutions for projects such as special ships, offshore modules, wind power facilities, etc. If you have specific project requirements, please submit drawings or specification information to obtain customized solution suggestions and quotation support. Quick Quote

Chalco bulb flat product technical parameters

Straightness - bow and camber

As measured over the length of the bar.

Twist

The permissible degree of twist is given as the following:

Twist can be difficult to measure and is easiest to measure converted into Torsion by measuring the Torsion T in mm and applying the following calculations:

Torsion, T (mm) = width (mm) x sin tol degree, x length (M)

Torsion: T = b x sin 0.35° x L - Special steel 1

Torsion: T =b x sin 0.5° x L -Standard steel

Flatness

The plate flatness tolerance h is 0.3% of the bulb flat width b and is measured as shown below.

Plate flatness tolerance: h ≤ 0.003 x b

The bulb flatness tolerance of the heel is n measured as shown below with a 2mm maximum.

Bulb flatness tolerance: n ≤ 2.0 mm

Bulb head dimensional tolerances overview

Item	Thickness t (mm)	Tolerance ≤	Item	Thickness t (mm)
Bulb head corner tolerance s	t ≤ 9	2.0 mm	Bulb head corner radius r₁	5 < t ≤ 9
	9 < t ≤ 13	3.0 mm		9 < t ≤ 13
	t > 13	4.0 mm		13 < t ≤ 20
Bulb head height tolerance f	t > 7	f ≤ 0.75 × s

Web edge dimensional tolerances overview

Item	Thickness t (mm)	Tolerance ≤	Item	Thickness t (mm)	Tolerance ≤
Web edge tolerance e	t ≤ 9	2.0 mm	Web edge angle tolerance w	t ≤ 9	4°
	9 < t ≤ 13	3.0 mm		9 < t ≤ 13	4°
	t > 13	4.0 mm		t > 13	4°

Surface condition

The surface requirements and repair conditions for shipbuilding profiles are in accordance

with EN10163-3:2004, subclass 3, class C. Maximum permissible depth of discontinuities and

grinding allowance below minimum specified thickness are given in the table below:

Requirements for blast-cleaned and primed material

The material can be delivered in blast-cleaned and primed condition in accordance with EN10238:1996.

The standard supply conditions are as follows:

Preparation grade: Sa 2½

Surface roughness: M (medium in acc. with ISO 8503-2)

Dry film thickness: 20μm ± 5μm

Types of primers: British Steel have painting facilities capable of applying a wide range of primers and can accommodate most customers preferred paints.

Size reference table

Aluminum Alloy Spherical Flat Profile Dimension Parameter Table
Thickness T1 (mm)	Width W1 (mm)	Thickness T2 (mm)	Width W2 (mm)	Length L (mm)
4.0	45	8	11.5	6000
5.0	50	8	12	6000
5.0	60	11	15	6000
6.0	85	15	20	6000
6.0	95	20	12	6000
4.5	50	—	14	6000
5.4	98.7	—	19	6000
5.6	76.2	—	19	6000
6.0	127	—	19	6000

Carbon steel bulb flat profile size parameter table
Size	Unit Weight 12m+ (kg)	b (mm)	t (mm)	c (mm)	r (mm)	Section (cm²)	Surface Area (m²/m)	Ixx (cm⁴)	Wxx (cm³)
60 x 4	35, 33	60	4	13	3, 5	3, 58	0, 146	12, 2	3, 2
60 x 5	41, 26	60	5	13	3, 5	4, 18	0, 148	14, 4	3, 89
60 x 6	47, 31	60	6	13	3, 5	4, 78	0, 150	16, 4	4, 55
80 x 5	53, 36	80	5	14	4	5, 41	0, 189	33, 87	6, 91
80 x 6	61, 23	80	6	14	4	6, 21	0, 191	38, 7	8, 1
80 x 7	69, 21	80	7	14	4	7, 00	0, 194	43, 3	9, 24
100 x 6	76, 47	100	6	15, 5	4, 5	7, 74	0, 235	76, 8	12, 7
100 x 7	86, 27	100	7	15, 5	4, 5	8, 74	0, 236	85, 3	14, 5
100 x 8	96, 32	100	8	15, 5	4, 5	9, 74	0, 238	94, 3	16, 3
120 x 6	91, 96	120	6	17	5	9, 32	0, 276	133	18, 5
120 x 7	103, 82	120	7	17	5	10, 52	0, 278	149	21
120 x 8	115, 68	120	8	17	5	11, 72	0, 280	165	23, 6
140 x 7	122, 21	140	7	19	5, 5	12, 43	0, 320	241	29
140 x 8	135, 52	140	8	19	5, 5	13, 83	0, 322	266	32, 5
140 x 9	150, 04	140	9	19	5, 5	15, 20	0, 324	291	36
140 x 10	165, 77	140	10	19	5, 5	16, 63	0, 326	315	39, 5
160 x 7	143, 99	160	7	22	6	14, 60	0, 365	373	38, 6
160 x 8	159, 72	160	8	22	6	16, 20	0, 367	411	43, 3
160 x 9	176, 66	160	9	22	6	17, 80	0, 369	449	47, 9
180 x 8	186, 34	180	8	25	7	18, 86	0, 411	609	55, 9
180 x 9	204, 29	180	9	25	7	20, 66	0, 413	664	61, 8
180 x 10	221, 43	180	10	25	7	22, 46	0, 415	717	67, 7
180 x 11	239, 58	180	11	25	7	24, 26	0, 417	770	73, 5
200 x 9	232, 32	200	9	28	8	23, 66	0, 457	942	77, 7
200 x 10	252, 89	200	10	28	8	25, 66	0, 459	1017	85, 1
200 x 11	273, 46	200	11	28	8	27, 66	0, 461	1091	92, 3
200 x 11, 5	283, 14	200	11, 5	28	8	28, 60	0, 462	1126	96, 2
200 x 12	291, 61	200	12	28	8	29, 66	0, 463	1164	99, 5
220 x 10	286, 77	220	10	31	9	29, 00	0, 503	1396	105
220 x 11	308, 55	220	11	31	9	31, 20	0, 506	1496	114
220 x 11, 5	319, 44	220	11, 5	31	9	32, 30	0, 506	1550	118
220 x 12	329, 12	220	12	31	9	33, 40	0, 507	1595	122
240 x 10	319, 44	240	10	34	10	32, 49	0, 547	1865	126
240 x 11	344, 85	240	11	34	10	34, 89	0, 549	1997	137
240 x 12	369, 05	240	12	34	10	37, 29	0, 551	2127	148
260 x 10	355, 74	260	10	37	11	36, 11	0, 591	2434	150
260 x 11	381, 15	260	11	37	11	38, 71	0, 593	2605	163
260 x 12	407, 77	260	12	37	11	41, 31	0, 596	2774	175
280 x 11	422, 29	280	11	40	12	42, 68	0, 637	3333	191
280 x 12	448, 91	280	12	40	12	45, 48	0, 639	3647	206
280 x 13	476, 74	280	13	40	12	48, 28	0, 641	3757	221
300 x 11	462, 22	300	11	43	13	46, 78	0, 681	4192	222
300 x 12	491, 26	300	12	43	13	49, 79	0, 683	4459	239
300 x 13	522, 72	300	13	43	13	52, 79	0, 685	4722	256
320 x 12	534, 82	320	12	46	14	54, 25	0, 728	5525	275
320 x 13	566, 28	320	13	46	14	57, 45	0, 730	5849	294
320 x 14	598, 95	320	14	46	14	60, 85	0, 732	6168	313
340 x 12	581, 28	340	12	49	15	58, 84	0, 772	6757	313
340 x 13	612, 26	340	13	49	15	62, 24	0, 774	7152	335
340 x 14	648, 56	340	14	49	15	65, 54	0, 776	7540	357
370 x 13	687, 28	370	13	53, 3	16, 5	69, 70	0, 840	9469	402
370 x 14	723, 58	370	14	53, 3	16, 5	73, 40	0, 842	9980	429
370 x 15	761, 09	370	15	53, 3	16, 5	77, 10	0, 844	10483	456
400 x 14	804, 65	400	14	58	18	81, 48	0, 908	12924	507
400 x 15	844, 34	400	15	58	18	85, 48	0, 910	13573	538
400 x 16	883, 30	400	16	58	18	89, 48	0, 912	14211	568

Chalco also provides other marine supporting materials

Chalco manufactures and supplies a wide range of bulb flats, flat bars and other shipbuilding structural products: the diversity of a factory, the flexibility of a dealer!

Plate

Flat/Square Bars

Equal / Unequal Angle

Half-round Bars

Round Bars

Pipes

Corrugated Plates

Beams

Inverted Angles

Frequently Asked Questions (FAQs)

Q: Can aluminum bulb profiles be used for structures?

A: Yes, it is especially suitable for light frame structures (such as yachts and car interiors). For high-strength structures, steel is recommended.

Q: Do you support custom sizes?

A: Of course, we can customize the size, alloy, surface treatment and other parameters.

Q: What standards do steel bulb profiles comply with?

A: GB/T 9945, EN 10067, JIS G3192, etc.

Q: Do you support small batch purchases?

A: Yes, we can provide low MOQ service for proofing or prototype projects.

Get a Quote / Contact Us

For enquiries or technical advice, please contact us:

• Request free samples and technical information
• Get a custom quote based on your drawing
• Professional alloy and structure selection suggestions