GR1, GR2, GR7: Li Hua Titanium's Complete Guide to Selecting Titanium Materials for Chlor-Alkali Pumps and Valves

In the extremely harsh corrosive environment of the chlor-alkali industry, the "health" of core components like pumps, valves, and pipelines directly determines production safety and efficiency. Titanium, with its unparalleled resistance to chloride ion corrosion, has become an indispensable key material.

However, when faced with different titanium grades like GR1, GR2, and GR7, many engineers and purchasing managers face a selection dilemma: What are the differences? Which one is truly suited for my specific working conditions?

Today, Li Hua Titanium, as a titanium flange expert deeply rooted in the chlor-alkali industry, will help you thoroughly understand these three commonly used titanium materials, providing an authoritative guide for your equipment selection.

GR1, GR2, and GR7 all belong to commercially pure titanium and titanium-palladium alloys. They share the core advantages of titanium metal:

• Excellent Corrosion Resistance: In oxidizing media (such as wet chlorine gas, hypochlorites in chlor-alkali production), they form a dense, stable oxide film, offering exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking caused by chloride ions – a key advantage over stainless steel.

• High Strength: Strength is close to that of ordinary steel, but density is only 60% of steel, effectively reducing equipment load.

• Good Processability: Possesses excellent forging, machining, and welding properties.

We can view GR1, GR2, and GR7 as a "pyramid" with progressively increasing performance and cost.

• Core Characteristics: Has the lowest content of impurity elements (like oxygen, iron) among commercially pure titanium grades, resulting in the best plasticity, toughness, and cold formability, but relatively lower strength.

• Key Data: Tensile Strength ≥ 240 MPa.

• Suitable Applications: Ambient or low-pressure environments with operating temperatures not exceeding 80°C. Sections with relatively weak corrosivity, such as storage tanks and heat exchange tubes for dilute alkali solutions and brine.

• Li Hua Recommendation: GR1 is the preferred choice for components with complex shapes requiring deep cold stamping. However, its strength requires careful evaluation for high-pressure pump and valve flanges.

• Core Characteristics: The most commonly used, comprehensively balanced commercially pure titanium grade. It achieves a perfect balance of strength, plasticity, and corrosion resistance, hailed as the "standard pure titanium."

• Key Data: Tensile Strength ≥ 400 MPa. This is the material specified for the vast majority of standard titanium flanges and titanium pipe fittings.

• Suitable Applications: Most常温 to medium-temperature (~150°C) conditions in chlor-alkali production. Flanges, pump casings, and valve bodies in core areas like the brine section, electrolyte streams, and wet chlorine gas pipelines.

• Li Hua Perspective: GR2 is the "workhorse" and "default option" for chlor-alkali pump and valve flanges. Unless specific conditions dictate otherwise, choosing GR2 is reliable for both performance and economy.

• Core Characteristics: Based on GR2, it adds approximately 0.12%~0.25% Palladium (Pd). This trace addition of a "noble metal" brings about a qualitative leap in corrosion resistance, particularly in reducing media and resistance to crevice corrosion.

• Key Data: Mechanical properties are comparable to GR2, but corrosion resistance is improved by orders of magnitude.

• Suitable Applications: High temperature, high concentration, acidic, or reducing media. Sections prone to crevice corrosion due to dead zones or gaps (e.g., at flange gaskets). Critical equipment where media composition is complex or fluctuates, requiring absolute reliability.

• Li Hua Interpretation: GR7 is your "ace card" for dealing with the most extreme and demanding conditions. It provides the highest safety margin. Although the initial cost is higher, its value in avoiding maintenance and replacement over the entire equipment lifecycle is immeasurable.

In the complex battlefield of the chlor-alkali industry, there is no "universal" material, only the "most suitable" solution. GR1, GR2, and GR7 form a complete material system covering conditions from routine to extreme.

Li Hua Titanium not only provides high-quality GR1, GR2, and GR7 titanium flanges that comply with ASTM, ASME, GB, and other standards but also aims to be your reliable consultant in equipment selection with our professional expertise. Let us work together to lay the strongest material foundation for the safe, efficient, and long-lasting operation of the chlor-alkali industry.