Swagelok DOT Sample Cylinder, Double-Ended and Single-Ended

Overview

The Swagelok sample cylinder is a pressure-rated container used to collect, hold and transport true samples of process gases and liquids from the plant to the laboratory. Swagelok builds each double-ended Swagelok sample cylinder from seamless tubing, which gives a consistent wall thickness, size and capacity from one cylinder to the next, and it offers single-ended cylinders for simpler sampling duties. The Swagelok catalog lists sizes from 10 cm3 up to 3785 cm3 (1 gal), working pressures up to 5000 psig (344 bar), and body materials in 304L and 316L stainless steel and alloy 400.

Seven Star LLC supplies the Swagelok sample cylinder range, together with the rupture disc units, valves and outage tubes that complete a sampling assembly, to refineries, gas processing plants, petrochemical units, power stations and laboratories in the Sultanate of Oman and across the GCC. Our Muscat team helps buyers translate a sampling procedure into a correct ordering number, and we provide model selection support from Muscat.

Key Features of the Swagelok Sample Cylinder

• Seamless tubing body: double-ended cylinders are formed from seamless tubing for consistent wall thickness and accurate internal volume.
• Smooth internal neck transition: the cylinder neck has no abrupt step, which makes cleaning easy and avoids pockets where fluid can be trapped between samples.
• Cold-formed female NPT threads: the end connections are cold formed for greater thread strength, and heavy-wall ends resist flaring when valves are installed.
• Corrosion-resistant low-carbon grades: 304L and 316L stainless steel resist intergranular corrosion; alloy 400 is available for more aggressive media.
• DOT conformance: Swagelok DOT sample cylinders conform to 49 CFR Part 178, the United States specification for packagings.
• Single-ended option: 150, 300 and 500 cm3 single-ended cylinders in 304L stainless steel, with full-penetration gas tungsten arc weld construction for leak-tight containment.
• Optional PTFE internal coating: for samples where surface adsorption or reactivity is a concern; ratings with the coating are limited to 300°F (148°C).

Swagelok Sample Cylinder Types and Pressure Ratings

Swagelok groups its cylinders by material and DOT specification. The catalog lists 304L and 316L stainless steel cylinders to DOT-3E 1800 with a working pressure of 1800 psig (124 bar), 304L to DOT-3A 1800, 316L to DOT-3A 5000 with a working pressure of 5000 psig (344 bar), alloy 400 to DOT-SP7458 1800, and single-ended 304L cylinders to DOT-4B 500 with a working pressure of 500 psig (34.4 bar). Ratings up to 100°F (37°C) are set by the DOT code, and the catalog provides derated working pressures at higher temperatures, so the selected Swagelok sample cylinder should always be checked against the hottest condition it will see in service.

Typical double-ended part numbers follow the pattern of material, cylinder style, end connection and volume, for example 304L-HDF4-500 for a 500 cm3 304L stainless steel double-ended cylinder with 1/4 in. female NPT ends, or 316L-HDF4-500 for the same volume in 316L stainless steel. Single-ended models such as 304L-05SF4-300 follow the same logic. Always confirm the final ordering number against the current catalog, because available combinations of volume and specification vary by material.

Testing and Traceability

Each DOT-rated Swagelok sample cylinder is hydrostatically tested to at least five-thirds of its working pressure. According to Swagelok, DOT-3E 1800 cylinders are proof tested at 3050 psig (210 bar) with one cylinder of each lot burst tested; DOT-3A 1800 cylinders are proof tested at a minimum of 3000 psig (206 bar); DOT-3A 5000 cylinders are proof tested at a minimum of 8500 psig (586 bar); DOT-SP7458 1800 cylinders are proof tested at 3000 psig (206 bar); and DOT-4B 500 cylinders at a minimum of 1000 psig (69 bar). DOT-3A cylinders are marked with a serial number, and their volumetric expansion during the hydrostatic test must stay within the limits of DOT specification 3A. The catalog also reminds users that the party filling a cylinder is responsible for having it retested by an approved facility at the required intervals.

Overpressure Protection and Accessories

Compressed gas cylinders must be fitted with suitable pressure relief devices in accordance with DOT regulations and CGA S-1.1. Swagelok rupture disc units vent the contents of a Swagelok sample cylinder to atmosphere if pressure rises beyond the disc rating. The disc is welded to a 316L body, sealed with a fluorocarbon FKM O-ring and uses an alloy 600 disc; nominal burst pressures listed in the catalog are 2850 psig (196 bar) for SS-RDK-16-2850 and 1900 psig (130 bar) for SS-RDK-16-1900. Rupture disc tees in 316 stainless steel, and nonrotating-stem needle valves with an integral rupture disc unit, allow the disc to be replaced without removing the valve from the cylinder.

A complete Swagelok sample cylinder assembly usually combines the cylinder with an isolation valve at each end, a rupture disc device, and, for liquefied gases, an outage tube that leaves a vapour space so the liquid can expand safely. Plants that build sampling panels frequently pair the cylinder with Swagelok SS-1RS4 integral bonnet needle valves for metering, QC series quick-connects for fast connection to the sample point, and Swagelok tube fittings for the panel tubing.

Applications in Oman and the GCC

• Spot sampling of natural gas, fuel gas and LPG into a Swagelok sample cylinder for laboratory composition and sulfur analysis.
• Transport of hydrocarbon liquid and condensate samples from wellsites, separators and storage tanks.
• Collection of reference samples for custody transfer disputes and quality certification.
• Calibration and validation gas handling in analyzer shelters.
• Sampling of corrosive or sour streams with alloy 400 cylinders where stainless steel is not suitable, subject to the plant materials engineer’s review.

Selection and Safe Use (General Guidance)

The following points are general engineering practice rather than manufacturer data. Choose the Swagelok sample cylinder volume to suit the laboratory test, allowing for repeat analyses. Select the material of the Swagelok sample cylinder to suit the sample chemistry and the plant’s materials philosophy. Make sure the working pressure, including derating for temperature, exceeds the maximum pressure at the sample point. For liquefied gases, use an outage tube and never fill a cylinder completely with liquid. Inspect rupture discs regularly, because Swagelok warns that temperature, corrosion and pressure cycling reduce burst pressure over time, and make sure the minimum burst pressure is at least 40 percent higher than the cylinder filling pressure. Clean, purge and label each Swagelok sample cylinder between uses to avoid cross-contamination.

Technical Specifications

How to Order

To order a Swagelok sample cylinder, send Seven Star LLC the sample medium, required volume, maximum pressure and temperature, material preference and the valves or rupture disc units you need. Our Muscat team will confirm the correct ordering number against the Swagelok catalog and prepare a formal quotation. The Swagelok sample cylinder catalog can be downloaded from this page, and we provide model selection support from Muscat for customers throughout Oman and the GCC.