【2026 Temperature Instruments】Comparison of differences between SH/T 3005 and HG/T 20507 regarding temperature instruments
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This post was last edited by The one on 2026-6-21 13:09. Both of these are design specifications for instrument selection; they have similar names but belong to two different industries: SH/T 3005 is a petrochemical industry standard, with temperature instruments covered in Chapter 5； HG/T 20507 is a chemical industry standard, with temperature instruments covered in Chapter 4. Regarding temperature, both are classified into the following three categories; the framework is consistent, but there are many differences in the specific provisions.
The overall impression is that this version of the regulations in the petrochemical industry is more detailed and imposes stricter requirements, especially in terms of precision tolerances, casing material, and safety interlocks； This version on chemical engineering is more concise, but it includes newer methods such as fiber-optic temperature sensing, hot spot detection, and radiometric pyrometers.
1. Precision and tolerances: The petrochemical version lists the tolerances for each division at different temperature ranges together with the calculation formulas in Table 5.3.9, allowing for direct access to the relevant values when needed. Table 4.3.1 in the chemical engineering version provides only the measurement range; it does not include tolerance formulas, so another source must be sought for selection purposes.
2. Casing material and insertion depth: The petrochemical version of the guidelines provides a dedicated comparison table (Table 5.3.11), which lists the maximum operating temperatures and suitable media for materials such as 316SS, Inconel, titanium, and tantalum. The chemical engineering version does not have this table; it only states in 4.1.3 that the selection should be based on design temperature, pressure, and corrosion resistance requirements. How deep to insert it is also specified in detail in the petrified version.
3. Transmitter installation location: If the environment is too hot or the transmitter is installed too high, it cannot be placed next to the temperature sensing element; instead, it must be installed separately. Both specifications require this, with the petrochemical version also including the height.
IV. Safety Interlocks: The petrochemical version places significant emphasis on interlock circuits; section 5.3.2 requires that the temperature sensing elements used for shutdown interlocks be installed separately, preferably in duplicate, and it is also recommended that transmitters have dual channels or be redundant. The chemical industry version does not have such a strict requirement – this is closely related to the serious consequences that can arise when there are problems with the interlocks in petrochemical continuous processes.
5. New Temperature Measurement Methods On the other hand, newer temperature measurement technologies are being more widely used in the chemical industry: fiber-optic temperature sensors (4.3.7) and hot spot detectors (4.3.8) are employed for large-scale monitoring in areas such as storage tanks, long-distance pipelines, cable trays, and cable trenches； When thermocouples are not suitable for extremely high-temperature environments, radiometric pyrometers can be used instead (4.3.5, 4.3.6). These items aren’t listed in the petrochemical version either. Ultimately, the focus is different: the petrochemical version delves more deeply into traditional contact-based temperature measurement, while the chemical version covers a wider range of applications.
6. Item-by-item comparison: the numbers in parentheses indicate the corresponding article numbers, to facilitate reference to the original text.
Speaking of temperature instruments as well, the petrochemical version (SH/T 3005) provides more detailed specifications and has stricter requirements, but it offers greater depth； The chemical industry version (HG/T 20507) is relatively concise, but it includes newer methods such as optical fibers, hot spot detection, and radiometric pyrometers, giving it an advantage in terms of breadth. The two don’t conflict with each other; simply choose the appropriate standard based on the industry to which the project belongs.