Analysis of the Extreme Environmental Adaptability of S690QL1 low temperature pressure vessel steel plate

In scenarios such as oil and gas exploitation, chemical storage and transportation in polar and alpine regions, S690QL1 low temperature pressure vessel steel plate has become the core material for manufacturing low-temperature pressure vessels due to its excellent low-temperature toughness. Compared with ordinary pressure vessel steel plates, S690QL1 (L1 represents low-temperature grade) can maintain no risk of brittle fracture in an extreme low-temperature environment of -40°C. Its performance advantages stem from precise composition control and stringent heat treatment processes.

First, from the perspective of composition design, S690QL1 strictly controls the content of harmful elements such as phosphorus (P≤0.025%) and sulfur (S≤0.015%) - these elements tend to form brittle inclusions in low-temperature environments, leading to a decline in the low-temperature toughness of the material. At the same time, nickel (Ni≤2.0%) is added to improve low-temperature toughness, and it is synergistically strengthened with elements such as manganese and molybdenum. This enables S690QL1 low temperature pressure vessel steel plate to meet the yield strength of 690MPa while having a low-temperature impact energy (-40°C) ≥60J, far exceeding the requirement of ordinary low-temperature pressure vessel steel (impact energy ≥27J).

• Chemical Composition for S690QL1 Steel Plate

In the heat treatment process, S690QL1 low temperature pressure vessel steel plate adopts a two-stage "quenching + tempering" treatment: the quenching temperature is controlled at 880-950°C to fully homogenize austenite, and a martensitic matrix is formed after rapid cooling; the tempering temperature is set at 550-650°C to eliminate quenching internal stress and precipitate fine carbonitrides, which not only ensures strength but also improves toughness. This process controls the grain size of the material above grade 6, and the fine-grained structure further enhances the low-temperature anti-brittle fracture capacity.

• S690QL1 Heat Treatment Parameters (English Table)

In practical applications, a polar oil and gas project used S690QL1 low temperature pressure vessel steel plate to manufacture an oil storage tank with a thickness of 28mm. In the measured environment of -42°C, after 1000 thermal cycle tests, the tank had no cracks or deformation, and the low-temperature impact energy at the weld joint remained above 55J. In contrast, the impact energy of a boiler steel plate of the same thickness in the same environment was only 22J, which was close to the critical value of brittle fracture.

In addition to low-temperature toughness, S690QL1 low temperature pressure vessel steel plate also has excellent weldability. When welding with low-hydrogen electrodes (such as E9018-G), the preheating temperature is controlled at 100-150°C, and stress relief treatment at 200-250°C is performed after welding, which can effectively avoid low-temperature embrittlement of welding joints. At the same time, it has a high matching degree between yield strength and tensile strength (yield ratio ≤0.85), and can effectively absorb stress in pressure fluctuation scenarios to avoid local overload failure of the vessel.

Regarding the testing standards for low-temperature pressure vessels, S690QL1 low temperature pressure vessel steel plate must pass multiple tests such as Charpy V-notch impact test, Ultrasonic Testing (UT), and Magnetic Particle Testing (MT) to ensure no internal defects. Compared with ordinary pressure vessel steel plate, S690QL1 has more stringent testing standards - for example, ultrasonic testing must meet Grade I of GB/T 6402-2018, while ordinary steel plates only need to meet Grade II.

Equivalent Grades Of S690QL1 Structural Steel Plate

In summary, S690QL1 low temperature pressure vessel steel plate has become the preferred material for pressure vessels in extreme low-temperature environments with the triple guarantees of composition, process and testing, providing stable material support for industrial production in alpine regions.

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FAQ

What is the difference between S690Q and S690QL?

S690Q: Minimum impact toughness tested at -20°C (30J average). → Typical Use: Cranes in temperate climates, quarry equipment. S690QL: Certified for -40°C and below (≥40J impact toughness). → Critical Use: Arctic pipelines, offshore platforms, mining vehicles in Siberia.

What grade is S690QL material?

S690QL is a high strength quenched and tempered steel grade that complies to steel specification EN 10025. The designation S690QL refers to a minimum yield strength of 690 MPa.

What is S690 grade steel?

S690 high yield & fine grain steel plate is a high strength, quenched and tempered fine-grain structural steel. Structural steel S690 is used in structures that must withstand very heavy loads. This grade is meant for structures where weight savings is important.

What is the equivalent of S690 steel?

Approximate equivalents
ASTM A514, EN 10149-2 Grade S700MC, AS/NZS 3579 Grade 700, AM 700, Bisalloy 80.

What is the price of S690QL material?

S690QL High Strength Steel Plates, Thickness: 5mm to 150mm at ₹ 135/kilogram in Mumbai.

What is the hardness of S690 QL steel?

S690QL steel stockholders and suppliers. S690QL is a quenched and tempered high strength steel supplied in full plates or cut pieces with delivery to the whole of the UK. With its high yield of minimum 690MPa it offers better strength than standard carbon steel grades.

What is the effective use of high strength S690 steel in construction?

The high strength S690 steels have an excellent strength-to-self-weight ratio, and they are highly efficient to be used in heavily loaded structures. Typical applications include piles and columns in buildings and supporting members in bridges.

What is the difference between S890QL and S690QL?

S690QL, S890QL, and S960QL are all water quenched and tempered steels that comply with the EN10025:6:2004 specification. These ultra high strength steels have a minimum yield strength of 690 MPa, 890 MPa, and 960 Mpa respectively, making them ideal for use in the haulage sector.

What is the difference between S700MC and S690ql?

The S700MC Steel is basically a structural steel plate developed especially for applications requiring high yield strength. They are used for several load bearing applications. The S690ql is a low alloy structural steel which is high in strength and comes with good weldability.

What is the yield strength of s690 steel?

690 MPa.

Yield strength of 690 MPa. Used in structures bearing extremely heavy loads, such as bridges, offshore drilling rigs and buildings, as well as in heavy construction equipment and cranes.