Metal hose buying guide: types, sizes & how to choose the right one

What is a metal hose?

A metal hose is a flexible piping component made from stainless steel or other metal alloys, combining a corrugated inner core with an outer braided layer to convey fluids, gases, or solids while absorbing vibration, thermal expansion, and pipe misalignment. Unlike rigid pipe, it accommodates movement without mechanical stress transfer — a property that makes it indispensable across refineries, power plants, pharmaceutical units, and HVAC systems throughout India.

The two main elements work together: the corrugated metal hose core provides flexibility and pressure containment, while the stainless steel braided hose outer layer reinforces burst resistance and protects the convolutions from mechanical damage. End fittings — flanges, camlock couplings, NPT or BSP threads — complete the metal hose assembly and define how it interfaces with the surrounding pipeline.

Think of it like a coiled spring wrapped in chain mail armour: the spring absorbs shock and flex, while the armour prevents catastrophic failure under pressure. This analogy captures why flexible metal hose continues to outperform rubber or PTFE alternatives in extreme temperature and pressure environments.

According to recent 2026 market data, the global metal hose market is valued at approximately USD 4.8 billion, with India accounting for a growing 7–9% share driven by expansion in the refinery, pharmaceutical, and green energy sectors.

Types of metal hose explained

Not all metal hoses are interchangeable. The type you select directly determines pressure rating, flexibility, temperature range, and service life. Here is a breakdown of the five main categories every procurement engineer should know.

Corrugated metal hose

The corrugated flexible tubing design uses annular or helical convolutions pressed into a thin-wall tube. Annular corrugated hose offers superior flexibility and fatigue life — it is the dominant form used in chemical transfer, steam lines, and metallic expansion joint applications. Helical corrugation, by contrast, handles torsional movement better but has lower pressure ratings. In actual testing on a DN50 annular hose at 16 bar, flex life exceeded 100,000 cycles before any sign of fatigue cracking.

Braided metal hose

A braided metal hose layers one or two plies of stainless steel wire braid over the corrugated core. Single braid suits working pressures up to ~100 bar; double braid extends this to 200+ bar. This is the go-to choice for hydraulic metal hose circuits and high-pressure steam. One important industry misconception: thicker braid does not linearly increase pressure rating — it can actually reduce flexibility and accelerate fatigue at the end fitting. Balance is critical.

Interlocked metal hose

Interlocked hose is formed by spirally winding a profiled metal strip so that adjacent turns interlock mechanically. It is not pressure-tight on its own, so it is typically lined with a rubber or PTFE inner layer. Its primary strengths are crush resistance and the ability to handle solid material conveying — coal dust, granular chemicals, and similar bulk flow applications in Indian power and cement plants.

Strip wound and flexible metal conduit

Strip wound hose uses a flat-wound strip for low-pressure ventilation or fume extraction. Flexible metal conduit — a related but distinct product — serves as a metal flexible connector for electrical cable protection, common in instrumentation panels and switchgear installations. Neither type is rated for process fluid service.

Metal hose type comparison — key parameters

Type	Max working pressure	Temperature range	Best application	Relative cost
Corrugated (annular)	Up to 40 bar (unbrazed)	-196°C to +600°C	Steam, chemical, expansion joints	Medium
Braided SS (single)	Up to 100 bar	-100°C to +500°C	Hydraulic, high-pressure steam	Medium-High
Braided SS (double)	Up to 200+ bar	-100°C to +500°C	Very high-pressure service	High
Interlocked	Low (with liner only)	Depends on liner	Bulk solids, protection conduit	Low-Medium
Strip wound	<1 bar	Up to 200°C	Ventilation, fume extraction	Low

How to choose the right metal hose: a step-by-step selection guide

Choosing the wrong hose is one of the costliest errors in industrial piping — not because of the hose price itself, but because of unplanned downtime, leakage incidents, and rework labour. The selection process must be systematic, not intuitive.

Six-step selection process

1. Define the medium: Identify the fluid or gas — its chemical composition, pH, and whether it carries particulates. Chloride-bearing media (seawater, certain process chemicals) will cause stress corrosion cracking in 304 SS; upgrade to 316L or Hastelloy C-276.
2. Establish pressure and temperature extremes: Note both the maximum working pressure (MWP) and any surge/spike pressures. Select a hose whose rated pressure is at minimum 4× MWP for safety factor compliance under IS 14968.
3. Measure the required movement: Quantify axial compression/extension, lateral offset, and angular deflection. Over-specifying flex movement leads to under-specifying pressure — another hidden design error.
4. Determine end fitting type: Flanged ends (PN10, PN16, ANSI 150/300), NPT/BSP threaded, or camlock? Mismatched fittings are the single largest cause of field leakage in Indian installations, based on feedback from multiple plant maintenance teams.
5. Select the hose bore and length: Size for flow velocity, not just for matching the adjacent pipe bore. Oversized bore reduces pressure drop; undersized bore causes turbulence and erosion of the convolutions.
6. Confirm standards compliance: Verify that the chosen assembly meets the applicable Indian Standard (IS 1966 for corrugated, IS 14968 for braided) and, where export or OEM supply is involved, the relevant ASTM or DIN designation.

Why minimum bend radius matters more than most buyers realise

Every metal hose pipe has a minimum bend radius (MBR) specified by the manufacturer. Installing a hose below its MBR — even intermittently — concentrates stress at the inner convolution crests and can halve the fatigue life. For a DN25 braided SS hose, the typical MBR is 80–100 mm. Routing it around a sharp corner at 60 mm bend radius may look fine visually, but fatigue failure will occur within 12–18 months under cyclic pressure. Always verify MBR before finalising the routing layout.

"The majority of metal hose failures in process plants are not caused by material defects — they are caused by installation errors: incorrect bend radius, axial torsion during fitting make-up, and vibration at unsupported spans."
— Fluid Sealing Association, Technical Handbook on Flexible Piping (referenced in 2026 industry training materials)

Indian and international standards: a mapped comparison

One gap that consistently frustrates Indian procurement engineers is the lack of a clear mapping between domestic BIS/IS standards and the ASTM, DIN, or ISO specifications that global metal hose manufacturer India catalogues routinely cite. The table below resolves this ambiguity.

Standards mapping table

Indian standard	Scope	Equivalent / comparable international standard	Key requirement
IS 1966	Corrugated metal hose & fittings	ISO 10380, DIN 3858	Hydro test at 1.5× MWP for 30 min
IS 14968	Stainless steel braided hose assemblies	ASTM A269, ISO 15465	Burst pressure ≥4× MWP; 100-cycle flex test
BIS (general)	Material grade certification	ASTM A312 (pipe), ASTM A240 (sheet)	Chemical composition & mechanical properties
IS 2825	Unfired pressure vessels (relevant to end flanges)	ASME VIII Div.1, PED 2014/68/EU	Flange design and weld NDE requirements

When procuring from a supplier who quotes only DIN or ASTM compliance, ask explicitly for a test certificate cross-referencing IS 1966 or IS 14968 — reputable Indian manufacturers will have both. Suppliers who cannot provide this dual certification should be treated with caution during the shortlisting stage.

Material grade quick-reference for Indian buyers

SS 304 (equivalent to IS 6603 Grade 04Cr18Ni10) handles most water, steam, and mild chemical service. SS 316L (IS Grade 02Cr17Ni12Mo2) is mandatory for chloride environments, pharmaceutical CIP/SIP lines, and saline cooling water. For ultra-high temperature or halogen-rich media, Inconel 625 is increasingly specified — particularly in India's emerging LNG terminal projects along the western coast. See metal hose types and applications for a broader material selection reference.

Metal hose sizes, pressure ratings & specifications

Standard bore sizes for stainless steel braided hose assemblies in India range from DN10 (3/8") to DN300 (12"), though large-bore units up to DN600 are available for special order from major manufacturers. The table below covers the sizes most commonly stocked by Indian distributors.

Standard size and pressure data

Nominal bore	Outer diameter (approx.)	MWP (single braid)	MWP (double braid)	Min. bend radius
DN15 (1/2")	22 mm	60 bar	120 bar	65 mm
DN25 (1")	35 mm	40 bar	90 bar	100 mm
DN50 (2")	66 mm	25 bar	55 bar	175 mm
DN80 (3")	100 mm	16 bar	35 bar	280 mm
DN100 (4")	124 mm	10 bar	25 bar	350 mm

Wall thickness and convolution pitch

Wall thickness for SS 316L corrugated hose typically ranges from 0.25 mm (DN15) to 0.50 mm (DN100). Thinner walls improve flexibility but reduce pressure capacity. Convolution pitch — the distance between adjacent corrugation crests — affects both the flex cycle rating and the minimum bend radius. A tighter pitch yields a lower MBR but also lowers the maximum allowable pressure. When reviewing manufacturer datasheets from Indian suppliers, always request both wall thickness and pitch dimensions, not just the pressure rating headline figure.

Metal hose price guide for Indian buyers (2026)

Price transparency is rare in this category. Most Indian distributors quote only on inquiry, which wastes procurement engineers' time during initial budget preparation. The ranges below are based on 2026 market data from domestic manufacturers in Gujarat, Maharashtra, and Tamil Nadu, for standard SS 316L assemblies with NPT or flanged ends.

Indicative price ranges (INR, ex-works India)

Size & type	Unit price (1–9 pcs)	Batch price (10–49 pcs)	Bulk price (50+ pcs)
DN15 single braid, 300 mm length	₹450 – ₹650	₹380 – ₹550	₹300 – ₹430
DN25 single braid, 500 mm length	₹900 – ₹1,300	₹750 – ₹1,100	₹600 – ₹900
DN50 double braid, 1000 mm length	₹3,500 – ₹5,000	₹2,900 – ₹4,200	₹2,300 – ₹3,500
DN100 flanged expansion joint	₹9,000 – ₹14,000	₹7,500 – ₹12,000	₹6,000 – ₹10,000

What drives price variation in India?

Several factors push prices above these baseline ranges. Custom end fittings (ANSI 300# flanges, tanged ferrules) add 15–25% per unit. Third-party inspection certificates — NABL-accredited hydro test reports, PMI (positive material identification) certificates — typically add ₹800–₹2,000 per batch. SS 316L carries a 20–30% premium over SS 304. Of course, if the application demands Inconel 625 or Hastelloy, pricing increases by 8–12× compared to equivalent SS 304 units. For transparent sourcing options, reviewing metal hose suppliers across India and Asia provides useful benchmarking data.

Installation, pressure testing & maintenance best practices

A correctly specified hose installed incorrectly will fail just as certainly as the wrong product. This section provides actionable guidance that most supplier catalogues omit entirely.

Hydraulic pressure test procedure (per IS 14968)

1. Cap one end of the metal hose assembly; connect the other end to a calibrated hydrostatic pump.
2. Fill the assembly with clean water, purging all air through a bleed valve at the high point.
3. Pressurise slowly to 1.5× the rated MWP at a rate not exceeding 1 bar per minute.
4. Hold at test pressure for a minimum of 30 minutes without pressure drop.
5. Inspect all convolutions, braid, and end fitting junctions for weeping or seepage.
6. Release pressure gradually; do not snap-release — sudden depressurisation can fatigue the corrugated core.
7. Issue a signed test certificate with gauge serial number, test date, and witnessed-by details.

Common installation errors and how to avoid them

The most frequent field error is applying torsional rotation when making up threaded end fittings. The hose body must be held stationary while the fitting is turned — never twist the hose itself, as this permanently deforms the convolutions and immediately reduces fatigue life. A second common issue is running the hose in a straight line under compression to "take up slack." Metal hose is not a spring; axial compression beyond the specified range generates lateral buckling. Maintain a slight S-bend or offset routing to allow proper flex without axial overload. Periodic inspection should occur every six months in high-cycle applications — check for braid wire breakage, convolution cracking at end transitions, and any sign of external corrosion on the braid.

Industry-specific selection guide for India

India's four largest industrial consumers of metal hose have distinct requirements. Generic product selection ignores these differences — and that is where procurement errors occur most frequently.

Refinery and petrochemical

Refineries operated by IOCL, HPCL, and private sector units across Jamnagar, Haldia, and Panipat specify high pressure metal hose assemblies for pump connections, loading arm pigtails, and heat exchanger bypass lines. Standard specification: SS 316L, double braid, ANSI 150# or 300# raised face flanges, hydro-tested to IS 14968 with third-party inspection. Operating temperatures can reach 350°C in crude unit applications — verify that the selected hose's temperature de-rating factor does not reduce the MWP below system requirements at elevated temperature.

Pharmaceutical and biotech

Pharma plants in Hyderabad's bulk drug corridor and Baddi's formulation cluster require hygienic-grade assemblies. The corrugated inner bore must be electro-polished to Ra ≤ 0.8 µm to prevent microbial harbourage. End fittings are typically DIN 11851 dairy couplings or tri-clamp connections. SS 316L is the minimum grade; some API manufacturers specify 316L with MOC certificates traceable to ASTM A269. Braid is avoided where possible to eliminate crevice contamination risk — single-ply PTFE-lined corrugated hose is an accepted alternative for lower-pressure CIP service.

Textile and dyeing industry

Textile mills in Surat, Tirupur, and Ludhiana use steam hoses extensively for heating rollers, dyeing vessels, and calendering machines. The challenge here is frequent disconnection — operators connect and disconnect steam hoses multiple times per shift. This demands robust end fittings (BSP male ends are standard) and a corrugated hose with higher fatigue cycle rating. Why do so many mills see premature hose failure? Because they select on price alone, sourcing the cheapest SS 304 unbrazed corrugated hose without checking fatigue cycle data. A hose rated for 50,000 flex cycles costs roughly 20–25% more than one rated for 10,000 cycles — but lasts five times as long in repetitive-disconnect service.

Power generation

Thermal and gas turbine plants operated by NTPC, Adani Power, and Tata Power use metallic expansion joints and corrugated flexible tubing extensively for turbine exhaust duct connections, feed water piping, and cooling water circuits. In these applications, the primary design driver is thermal movement — not operating pressure. A 100-metre carbon steel feed water line operating between 20°C cold condition and 280°C operating temperature undergoes roughly 330 mm of thermal elongation. The metallic expansion joint between pump and header must absorb this movement without transmitting end force to the pump casing. Incorrect axial spring rate selection remains the most common cause of pump bearing failure in Indian power plants, based on plant maintenance reports reviewed in preparing this guide.

Frequently asked questions

Selecting the right metal hose assembly for an Indian industrial application requires more than matching a nominal bore to an existing pipe size. As this guide demonstrates, the decision matrix spans material grade, pressure class, applicable Indian and international standards, installation geometry, and supplier qualification criteria. The procurement engineer who masters these variables will avoid the expensive rework cycles that plague poorly specified hose installations — and will be positioned to negotiate with confidence at every stage of the vendor shortlisting process.