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About UsTsisco Industrial Ltd. was established in 2010. Originating from the Tsingshan ecosystem’s Shanghai platform, the company now operates independently and focuses on global supply-chain integration, distribution, and import/export of steel and alloy materials. We achieved ISO 9001 certification from TÜV Rheinland in 2012, and ISO 9001, ISO 14001 and ISO 45001 certifications from LRQA in 2022. These accreditations underpin continuous improvement and stable performance in quality, environment, and occupational health & safety.
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Products & Solutions
Stainless Hollow Bars
Stainless Hollow Bars
Hollow Bar｜Global Sourcing for Engineering & Procurement
1. Product Positioning & Scope
• Definition: Hollow bar is a thick-wall, hollow long product for machining. It focuses on machining allowance, concentricity, and straightness, and is typically supplied to EN 10294 or mechanica-tube standards.
• Industries: General machinery, mining and metallurgical equipment, petrochemical components, pulp and paper machinery, pump/valve and hydraulic blanks, offshore and seawater components, non-process-side structures in food and pharma equipment.
• Boundary to “pipe”: Hollow bar is not a pressure pipe. For pressure service, project specifications and code add-ons must be written into the contract and verified.
• Supply forms: As-rolled black surface or solution-annealed and pickled (HRAP). Optional OD/ID machining allowance and end finish per project.
2. Standards Matrix (by use and alloy family)
• Hollow-bar and mechanica-tube base:
— EN 10294-1: Hollow bars for machining — non-alloy and alloy steels.
— EN 10294-2: Hollow bars for machining — stainless steels.
— EN 10297-1: Seamless circular steel tubes for mechanical and general engineering purposes.
— EN 10305-1: Cold-drawn precision seamless tubes (for tight tolerances and surface).
— ASTM A519: Seamless carbon and alloy steel mechanical tubing.
— ASTM A511: Seamless stainless steel mechanical tubing.
• Dimensions & tolerances (stainless and negotiated cases): ISO 1127 as a reference when stainless “tube route” is adopted for hollow-bar use.
• Nondestructive testing: EN ISO 10893 series (UT, ET, RT, MT, PT methods and levels).
• China/Japan cross-references: GB/T 8162, GB/T 3639, GB/T 14975／14976／13296 (when using tube route); JIS G3445, JIS G3459.
• Certifications and witnessing: EN 10204 3.1／3.2.
3. Scenario—Material—Standard—Size Mapping (quick text guide)
• General sleeves and bushings: Materials E355, 20MnV6, 42CrMo4 (AISI 4140). Standards EN 10294-1 or ASTM A519. Typical OD 60–250 mm, WT 10–60 mm, L 4–6 m.
• High strength and fatigue-sensitive rings and couplings: Materials 42CrMo4 (QT), 34CrMo4 (AISI 4130). Standards EN 10294-1 or ASTM A519. Typical OD 80–300 mm, WT 20–80 mm.
• General corrosion-resistant structures (non-process side): Materials 304L, 316L. Standards EN 10294-2 or ASTM A511. Typical OD 50–200 mm, WT 8–40 mm.
• Seawater and high-chloride service: Materials duplex 2205, super duplex 2507. Standard EN 10294-2; if using tube route, add ASTM A789 chemistry and corrosion checks. Typical OD 60–220 mm, WT 10–50 mm.
• High-temperature oxidation or strong-corrosion parts: Materials 310S, Ni-alloys 625, 825, C-276. Standard ASTM A511 or relevant Ni-alloy tube/bar standard plus mill technical conditions. Sizes per capability.
• Tight fit with high ID surface quality: Use EN 10305-1 cold-drawn precision route, or stipulate ID finish and roughness on top of EN 10294; tighten tolerances by agreement.
4. Size Range & Tolerances (negotiable tightening)
• Outside diameter: ~30–250 mm mainstream; larger ODs available subject to mill capability.
• Wall thickness: ~8–80 mm common; thicker walls by project.
• Length: typically 4–6 m; fixed lengths available.
• Straightness: typically ≤1.5 mm/m; tighter limits per project.
• Eccentricity & ovality: write explicit limits into the PO; typical eccentricity ≤10%. Ovality per EN 10294 or agreement.
• Tolerance system: follow EN 10294-1／-2 for OD/WT/length/straightness; if supplied to ASTM A519 or ASTM A511, apply those standards’ tolerance clauses; for stainless tube route, ISO 1127 D/T classes may be adopted by agreement.
5. Manufacturing Flow & Key Controls
• Steelmaking & refining: EAF/BOF with AOD/VOD; ESR as needed; ensure low S/P and cleanliness.
• Forming: Mannesmann piercing with hot rolling or hot extrusion to thick-wall hollows; control wall uniformity and concentricity.
• Heat treatment: Normalize or quench & temper for C-Mn/alloy; solution anneal and rapid cool for stainless to avoid harmful phases.
• Straightening & NDT: Straighten and test per EN ISO 10893 series (UT/ET/MT/PT); 100% UT recommended for critical parts.
• Machining allowance & ends: Define OD/ID allowances; face and chamfer ends for clamping and boring.
6. Quality Checks & Documentation
• Chemistry & PMI: per grade and standard; positive material identification at critical points.
• Mechanical properties: YS, UTS, EL, hardness per standard and delivery condition.
• Dimensions & surface: OD, WT, L, straightness, ovality, eccentricity; no laps, cracks, seams, or deep scratches.
• Tightness & pressure: Hollow bar is not a pressure pipe; add leak or pressure tests only if specified for pressure-part blanks.
• Dossier: EN 10204 3.1／3.2, heat-treatment charts, NDT reports, dimensional records, traceability; third-party witnessing as specified.
7. Supply Forms & Packing
• Supply condition: black, pickled, or solution-annealed and pickled (HRAP).
• Protection: stainless pickling and passivation; end caps; rust and moisture protection.
• Marking & traceability: heat/lot, grade, size, length, condition, weight, piece ID; QR if required.
8. Ordering Checklist (copy-paste ready)
1. Standard & edition: EN 10294-1／-2 or ASTM A519／ASTM A511 (year). If tube route is used, add EN 10297-1／EN 10305-1 or ISO 1127 clauses.
2. Grade & condition: e.g., “42CrMo4 + QT”, “1.4462 (2205) solution annealed”.
3. Size & tolerances: OD × WT × L; limits for straightness, eccentricity, and ovality; machining allowance if any.
4. NDT: UT/ET coverage and level; MT/PT if needed.
5. Documents & witnessing: EN 10204 3.1／3.2, heat-treatment charts, NDT reports, TPI list.
6. Packing & logistics: end protection, anti-rust and moisture protection, handling and stacking requirements.
9. Material Selection Guide (text)
• Cost and machining efficiency: E355, 20MnV6 (EN 10294-1).
• Strength and toughness: 42CrMo4 QT or AISI 4140 (ASTM A519).
• General corrosion resistance: 304L, 316L (EN 10294-2 or ASTM A511).
• Seawater/chlorides: 2205 or 2507 (EN 10294-2; add ASTM A789 requirements where applicable).
• High-temperature/strong corrosion: 310S, Alloy 625／825, C-276 (check mill capability and heat-treatment window).
10. Procurement, Installation & O&M Risk Alerts
• Treating hollow bar as pressure pipe without code add-ons creates compliance gaps.
• Missing limits for straightness/eccentricity/ovality leads to scrap after machining.
• No pickling/passivation or iron contamination on stainless surfaces causes early pitting.
• Using 304/316 in seawater/high-chloride service reduces life; switch to duplex or Ni-alloys.
• Not defining EN ISO 10893 methods/coverage risks hidden internal defects.
• Tight-ID applications require agreed ID roughness and finishing plan in advance.
11. Representative Purchase Lines (ready for RFQ/PO)
• Alloy-steel sleeve blank:
“Hollow bar: EN 10294-1 E355 + SR, OD 180 mm × WT 30 mm × L 6 m; machining allowance +2.0 mm OD / +2.0 mm ID; straightness ≤1.5 mm/m; 100% UT (EN ISO 10893-8 level as agreed); EN 10204 3.1.”
• High-strength ring blank (QT):
“Hollow bar: ASTM A519 4140 Q + T (28–32 HRC), OD 260 mm × WT 45 mm × L 5.8 m; UT level E2; ends chamfered; EN 10204 3.1.”
• Stainless corrosion-resistant part:
“Hollow bar: EN 10294-2 1.4404 (316L) HRAP, OD 150 mm × WT 20 mm × L 6 m; pickled & passivated; 100% UT; EN 10204 3.1.”
• Offshore duplex component:
“Hollow bar: EN 10294-2 1.4462 (2205) solution annealed, OD 120 mm × WT 18 mm × L 6 m; phase balance 35–60%; verify ASTM A923 Methods A/B/C and G48-A @ 25 °C; 100% UT; EN 10204 3.2.”
12. Representative Global Producers (alphabetical, examples)
• Alleima (ex-Sandvik Materials Technology): Sanmac hollow bars including duplex series.
• Benteler Steel/Tube: European mechanical tubes and hollow bars.
• OSTP (ex-Outokumpu Stainless Tubular Products): stainless hollow bars and tubes.
• TimkenSteel: alloy mechanical tubing and hollow bars (ASTM A519).
• Tubacex Group: stainless and high-alloy tubes and hollow bars (EN/ASTM systems).
• voestalpine Tubulars: mechanical tubes and hollow bars in Europe.
• Salzgitter Mannesmann: EN 10294-1 hollow bars and stock size systems in Europe.
Hollow Bar｜Technical Specifications
1. Definition and Scope
1. Definition: Hollow bar is a thick-wall, round, cored long product intended for machining (turning, boring). It is produced by piercing plus hot-rolling or hot extrusion, followed by heat treatment, straightening, dimensional control with machining allowances, and NDE. The dedicated European product standards are EN 10294-1 (non-alloy and alloy steels, hollow bars for machining) and EN 10294-2 (stainless steels, hollow bars for machining).
2. Boundary to “pipe/tube”: Hollow bar is supplied as machining stock and shall not be treated as a code-stamped pressure pipe. For pressure service or heat-exchanger use, apply the relevant tube/pipe standards (e.g., ASME/ASTM A312, A213, A269, A789) instead of hollow bar.
3. Typical industries: General machinery, mining and metallurgical equipment, rollers, couplings, bushings and sleeves, pump/valve and hydraulic components (as blanks), offshore/non-media-side structures, paper and fiber machinery.
4. Not for: regulated pressure service unless the applicable codes (ASME/PED) and add-on requirements are fully met by contract.
2. Standards Landscape
2.1 Hollow-bar & mechanical-tube standards
• EN 10294-1: Hollow bars for machining – non-alloy and alloy steels; dimensions, tolerances, technical delivery conditions.
• EN 10294-2: Hollow bars for machining – stainless steels.
• EN 10297-1: Seamless circular tubes for mechanical and general engineering purposes – often referenced for hollow-bar deliveries.
• EN 10305-1: Steel tubes for precision applications – cold-drawn seamless (for tighter tolerances and improved bore finish).
• ASTM A519: Seamless carbon and alloy steel mechanical tubing (commonly used in the U.S. as a hollow-bar equivalent).
• ASTM A511/A511M: Seamless stainless steel mechanical tubing (for stainless hollow-bar deliveries).
• ISO 1127: Stainless steel tubes – dimensions and tolerances (used as a negotiated reference when pipe-route products are supplied as hollow-bar blanks).
• EN ISO 10893 series: NDT of steel tubes (UT/ET/RT/MT/PT) – to be specified for hollow-bar/mechanical-tube NDE.
2.2 Common supporting standards in China/US/Japan
• China GB/T: GB/T 8162 (structural seamless), GB/T 3639 (cold-drawn precision seamless); stainless routes GB/T 14975 (structural), GB/T 14976 (fluid), GB/T 13296 (boiler/heat-exchanger) when pipe-route is used as hollow-bar blanks.
• US ASME/ASTM (pipe/tube for pressure service, for boundary clarification): A312, A213, A269, A789.
• Japan JIS: G3445 (machine structural carbon steel tubes), G3459 (stainless steel pipes).
Note: ISO 2938 (“Steel — Hollow bars for machining”) has been withdrawn; use EN 10294 series instead.
3. Grades (examples)
• Carbon & low-alloy: E355 (1.0580), 20MnV6 (1.5217), 42CrMo4 (1.7225 ≈ AISI 4140), 34CrMo4 (≈ 4130), E470/E590 – for general machining, couplings, sleeves and rollers.
• Stainless: 304/304L (1.4301/1.4307), 316/316L (1.4401/1.4404), 321, 347, 310S, 904L (1.4539), 6Mo (UNS S31254, 1.4547), duplex 2205 (1.4462), super duplex 2507 (1.4410).
• Nickel alloys: Alloy 625 (UNS N06625), 825 (UNS N08825), Hastelloy C-276 (UNS N10276) – for severe corrosion/high-temperature carburizing; typically supplied per A511 or per manufacturer’s conditions.
4. Manufacturing and Heat Treatment (Process and Control Essentials)
• Melting and billets: EAF/BOF → AOD/VOD (for stainless steel) refining; ESR when required; supply as continuous-cast billets or ingots.
• Forming: Piercing (Mannesmann) plus hot rolling or hot extrusion to produce a thick‑wall hollow shell; when necessary, perform rough machining after heat treatment to control machining allowance.
• Heat treatment:
– Carbon/alloy steels: Normalizing; quench‑and‑temper (Q+T); or normalize plus temper, to achieve the required strength, toughness, and machinability.
– Stainless steels: Solution annealing (typically ≥1040 °C, per the applicable grade standard) followed by rapid cooling to prevent precipitation of deleterious phases (σ/χ).
• Straightening and NDE: In‑line or off‑line straightening; carry out UT/ET/MT/PT in accordance with the EN ISO 10893 series (coverage as specified by the project). Because hollow bar is commonly supplied as a machining blank, control straightness and residual stress in the delivery condition to reduce distortion during subsequent turning.
• Machining allowance and ends: Define OD and ID machining allowances; face and chamfer ends to facilitate later clamping and boring.
5. Dimensions, Wall Thickness & Tolerances
Typical stock OD ranges around 30–250 mm (wider ranges available depending on mill capability). Apply EN 10294-1/-2 tolerances for OD, wall and length when hollow-bar route is specified; for pipe-route products (A519, A511, EN 10297-1, EN 10305-1), tolerances follow the respective tube standards; for stainless, ISO 1127 tolerance classes can be referenced by agreement. Specify limits for wall-thickness eccentricity, ovality and straightness in the PO.
6. Surface & Cleanliness
Supply as black or pickled/shot-blasted; no laps, folds, cracks or deep scratches. Stainless hollows shall be pickled and passivated (or mechanically de-contaminated) to minimize pitting initiation; specify cleanliness and residuals for clean-service industries.
7. QA/QC & Testing
Chemistry (incl. PMI if required); tensile/elongation/hardness per standard and HT condition; NDE per EN ISO 10893 (coverage to be defined, e.g., 100% UT for critical parts); dimensional checks (OD/WT/length/straightness/ovality/eccentricity); hydro/helium tests only when contractually required; documentation per EN 10204 3.1/3.2.
8. Service–Grade–Standard–Size Mapping (text quick guide)
• General machining (bushings, sleeves, couplings): E355, 20MnV6, 42CrMo4 → EN 10294-1 → prioritize stock OD 30–250 mm.
• High strength & toughness: 42CrMo4 Q&T or AISI 4140 → EN 10294-1 or ASTM A519.
• Corrosion-resistant (food, paper, general chemical): 304L/316L → EN 10294-2 or ASTM A511 → tolerances negotiable per ISO 1127.
• Chloride/sea-water/offshore: Duplex 2205/2507 → EN 10294-2; or pipe-route with ASTM A511/A789 as applicable.
• High-temperature/severe corrosion: 310S, Alloy 625/825, C-276 → per A511 or manufacturer’s spec with HT/structure control.
9. Ordering Checklist
Standard & edition (EN 10294-1/-2; or ASTM A519/A511; add EN 10297-1/EN 10305-1/ISO 1127 if pipe-route); grade & HT condition; OD × WT × length; limits for straightness/ovality/eccentricity; NDE method & coverage; documentation (EN 10204 3.1/3.2); end protection, rust prevention and marking.
10. Pitfalls (corrections & avoidance)
Misusing hollow bar as pressure pipe; relying on withdrawn ISO 2938; missing eccentricity/straightness limits; inadequate stainless de-contamination; using 304/316 in high-chloride service; insufficient NDE per EN ISO 10893.
11. Selection Guide (summary)
Cost-efficient machining → E355/20MnV6; strength/toughness → 42CrMo4 (Q&T)/4140 (A519); general corrosion → 304L/316L (EN 10294-2 or A511); chloride/sea-water → 2205/2507 (EN 10294-2 or A789 via pipe-route); high-T/corrosion → 310S/625/825/C-276 (confirm manufacturability & HT window).
12. Representative Global Manufacturers (examples, A–Z)
Alleima (Sanmac® hollow bar); Benteler Steel/Tube; OSTP; TimkenSteel; Tubacex Group; voestalpine Tubulars; Salzgitter Mannesmann/T&S distribution.
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