Sanitary Tube Standards: ASTM A270, DIN 11850 (EN 10357), ISO 2037 and SMS 3008

There are a bunch of standards for sanitary tubes and fittings thrown around in the food, beverage, and pharmaceutical industries today. Because these standards originate from different countries, they often overlap and cause confusion among engineers and production people.

This article aims to breakdown the most common of these standards: ASTM A270, DIN 11850, EN 10357, ISO 2037 and SMS 3008.

Quick comparison

Standard	Origin	Size basis	Typical Connection
ASTM A270	USA	Inch OD (1", 1.5", 2", etc)	Tri clamp
DIN 11850 / EN10357-A	Germany / Europe	Metric by DN (OD29, 41, 53mm, etc)	DIN 11851 union
ISO 2037 / SMS 3008	Sweden / International	Metric OD (25, 38, 51mm, etc)	SMS union

Common sizes

Size	ASTM A270 (OD x Thickness)	DIN 11850 / EN 10357-A (OD x Thickness)	ISO 2037 / SMS 3008 (OD x Thickness)
1" / DN25	25.4 x 1.65mm	29 x 1.5mm	25 x 1.2mm
1.5" / DN40	38.1 x 1.65mm	41 x 1.5mm	38 x 1.2mm
2" / DN50	50.8 x 1.65mm	53 x 1.5mm	51 x 1.2mm

ASTM A270

ASTM A270 is the North American standard for stainless steel sanitary tubing. It is mostly about the manufacturing process, materials, dimensions, and surface finish.

• Materials: 304, 304L, 316, or 316L stainless steel

• Dimensions: Measured in inches

• Surface Finish: Defines specific Ra (Roughness Average) values, often requiring Ra0.8 for standard food grade.

3A (a different type of standard)

3A is not a tube size standard. This standard makes sure that 3A Sanitary Fittings, Valves, and Tubes are designed with safety in mind, making sure that equipment is easy to clean and inspect. Read more in our post about the 3A standard.

EN 10357

This is the modern European standard for stainless steel tubes. It was created to consolidate various national standards across Europe into one.

• Structure: It is divided into different series:

  • Series A: Based on the old DIN 11850 Series 2 (The most common in Europe).

  • Series C: Based on ASME BPE dimensions (Imperial sizes in metric units).

  • Series D: Based on ISO 2037, similar to SMS dimensions.

• Scope: It covers dimensions, tolerances, materials, and surface conditions.

DIN 11850

Before the EN10357, DIN 11850 was used for German sanitary engineering. While it has been officially superseded by EN 10357 Series A, many engineers and procurement systems still refer to DIN 11850.

DIN 11851: DIN Union

While the standards above define the tubes, DIN 11851 is a threaded union that defines how they are connected. It is arguably the most recognizable threaded fitting in the hygienic world. It consists of a threaded male part, a liner, a round slotted nut, and a D-shaped gasket.

ISO 2037 and SMS 3008

Before EN10357, ISO 2037 served as one of international standard for stainless steel tubes for the food industry. It was mainly derived from the SMS 3008 standard from Sweden, which was a powerhouse in dairy engineering. It is superseded by EN10357 series D, but most engineers still prefer to call it the ISO/SMS standard.

• Dimensions: It is very similar to the Swedish SMS 3008 standard and is often used in Southeast Asian and Australian markets where a mix of European and US equipment is common.

• Surface: It specifies a maximum surface roughness of Ra = 1.0 for the internal weld and 0.8 for the parent metal.

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NKE Flow is a supplier of sanitary tubes, fittings, and valves in Malaysia. Contact us for more information.