Hex Design Features
 Pressure/Temperature Chart
Stem/Seat Configurations (For Gauge, Root/Isolation and Block & Bleed
Stem/Seat Configurations (Manifolds)
VOC Emission Compliance
| Bonnet Assembly Design: Hex offers a time-tested, metal-to-metal body/bonnet seal with the largest stem diameter in the industry. Hex offers a proven Chevron design multipoint packing and Graphite/Grafoil wiper ring arrangement. |
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Benefit |
Feature |
Advantage |
| Our stems will provide longer service life, particularly under adverse conditions. |
Minimum diameter of the Hex stem is larger than any competitor. |
Our stem is less likely to break under normal and excessive rotational torque. |
| Hex valves are less likely to leak (emissions) than the competitors' standard design, minimizing emission auditing costs. |
Packing: four rings of Teflon Chevron for low to medium temperature. High temp packing is Grafoil packing sandwiched between two braided graphite rings. |
Our packing seats offer a better seal; Hex Valve standard packing sets meet EPA 1998 leak point standards. |
| Our stem tip design will last longer than competitors. |
Non-Rotating Tip Stem (NRT) |
Offers tight, repeatable shutoff without the galling or cross-scoring that occurs on ball-type stems. The NRT conical stem tip stops rotating when it contacts the seat so further torque turns the stem, not the tip. Furthermore, the conical stem tip seats in the same place every time - the more often the valve is seated, the better mated it becomes with the seat. By contrast, the ball-type tip does not seat in the same place every time, as the ball tip has no consistent axis of rotation. Therefore, every time the valve seats, a new seat mark is scored on the ball tip, creating multiple potential leak paths. |
| Packing is adjustable, with less possibility of bonnet/body leaks |
Metal-to-metal non-adjustable body-to-bonnet seal. |
Some bonnet designs have soft, elastomer or plastic seal rings increasing the possibility of stem leakage if excesses in temperature or pressure occur. Secondly, these other inferior designs require you to rotate the body-bonnet connection in order to access or adjusting the packing. The Hex Valve body/bonnet connection is static and non-adjustable. |
NACE Specifications
Sour service covers hydrocarbons, notably petroleum crudes and gases containing sulfur in the form of hydrogen sulfide (H2S). The corrosion phenomenon causing concern is referred to as sulfide stress cracking (SSC). Most ferrous metals, when hardened by heat treatment or cold working to hardness above Rc22, are susceptible to sulfide stress cracking when exposed under stress to a sour environment.
Equipment used in instrument systems operating in sour gas service will require conformity to the NACE (National Association of Corrosion Engineers) Standard MR-01-75.
General Requirements:
Carbon and low alloy steel shall not be harder than Rc22 in the finished condition, and must be either hot rolled, annealed, normalized, quenched and tempered, or stress relieved.
Free machining steels shall not be used.
Low and medium alloy steels containing less than 12% chromium and/or more than 1% nickel shall not be used.
Inconel shall not be harder than Rc35 in the finished condition.
K-Monel shall not be harder than Rc32 in the finished condition, and must be age hardened or solution annealed.
Carbon Steel bolting shall conform to ASTM A-193, grade B-7M, and ASTM A-194, grade 2HM specifications. Pressure-containing bolting shall conform to sour gas requirements specified in above points whether they contact the sour service or not.
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