Why Choose OMSS Rectangular Manway?
- Over 15 years of manufacturing experience in stainless steel rectangular manways.
- High-power laser cutting machine, controlling dimensional accuracy to the millimeter level.
- Professional R&D team, completing non-standard customized solutions within 24 hours.
- Regular stock of 304, 304L, and 316L stainless steel, reducing procurement time.
- Packaging separately and securing, keeping the structure intact during transportation.
OMSS-Your Professional Rectangular Manway Manufacturer in China
OMSS is a professional stainless steel rectangular manway manufacturer in China, committed to solving leakage and deformation issues of rectangular manways. They are made from high-quality stainless steel and use reinforcing ribs and locking structures to ensure door panels remain in frequent opening and closing. We use sealing rings made from different materials, ensuring zero leakage under high-pressure conditions.
Our stainless steel rectangular manways support full customization, including opening size, surface treatment, opening direction, and additional parts. They are widely used in equipment storage tanks, reaction vessels, and other equipment.
Types of Rectangular Manways
Installed on the side wall of the tank, convenient for personnel to enter, commonly used for fermentation tanks, chemical storage tanks, etc.
Installed on the top of the tank, serving both feeding and maintenance purposes. Commonly used for food processing tanks, small containers, etc.
Locked by hinges and handwheels. Its adjustable hinge design compresses the rectangular manway and avoids falling when opened.
With a removable cover, providing an opening space without barriers. It is used in large equipment pass through scenarios or limited opening positions.
Uses a multi-handwheel locking structure with good sealing performance and can adapt to pressure storage tanks and chemical reactors.
Simple structure and lower cost, suitable for general storage tanks and water tanks. Easy handles or latches can be added according to requirements.
Features of Rectangular Manways
Made of 304/304L/316L stainless steel and chemical-resistant manway gaskets, maintaining good corrosion resistance in highly corrosive environments.
Uses a rounded arc transition design to prevent damage at corners and extend the service life of rectangular channels.
High-elasticity gaskets and precisely machined sealing grooves ensure airtightness, effectively preventing the leakage of gases, liquids, and dust.
Made of thickened stainless steel, the hinges can be frequently opened and closed without moving, ensuring tight sealing of the rectangular manways.
The surface is polished to ensure smoothness and is not easy to accumulate dirt and convenient to clean.
Choosing different materials of gaskets according to the temperature, which can adapt to a temperature range of -50℃ to 250℃.
Cut using a laser cutter, with dimensional accuracy controlled at the millimeter level, facilitating subsequent welding.
The handwheel and handle are ergonomically designed for easy operation even with gloves, reducing work intensity and increasing worker efficiency.
Easy Opening
For heavy rectangular manways weighing 20-50kg, we use assisted gas springs. When opening the panel, the high-pressure nitrogen inside provides a compensating force, which offsets most of the weight. It also allows the panel to hover at any angle. This device improves the opening efficiency of panels and prevents finger injuries from sudden closures, saving you workers’ compensation costs.
Reinforced Hinge Load Bearing
The fixed moving path of the hinge allows the panel to close accurately. Its strength is very important because the hinge bears the gravity of the panel. If the strength is insufficient, the hinge may sag or title in long-term use, causing the panel to close improperly or seal tightly. Our hinge base plate has a thickness of over 16mm, uses double-sided full welding, enabling it to withstand more than 100,000 normal uses while ensuring the panel position remains unchanged.
Application of Rectangular Manways
Sanitary standards are the most important factor. Our hygienic manway for food processing is made of stainless steel and mirror-polished, with an inner wall roughness (Ra) ≤ 0.6 μm. This prevents food residues from adhering to cracks or corners and avoids bacterial growth. Their excellent corrosion resistance enables frequent CIP cleaning in the food industry, making them commonly used in wine, juice, and other brewing and storage tanks, as well as CIP cleaning tanks.
Compared to food industries, rectangular manways in biotechnology require stricter inner surface specifications, usually with a roughness of Ra < 0.2μm – 0.4μm, to prevent microorganisms in tiny gaps. The sealing gaskets have passed FDA standards and U.S. Pharmacopeia toxicity tests. They will not release substances even during high-temperature steam sterilization. Stainless steel rectangular manways are often used in pharmaceutical mixing tanks and sterile storage tanks.
The chemical industry often transports corrosive media such as strong acids, strong bases, and organic solvents, which have high requirements for sealing and corrosion resistance. The rectangular manways have chemical-grade corrosion resistance and are often used in chemical storage tanks. The R-angle transition design and high-sealing gaskets ensure no leakage under high-pressure conditions, such as reactors.
Rectangular manways in the energy industry have high requirements for sealing to prevent the leakage and spread of harmful volatiles in crude oil and refining products. The light components in crude oil have strong permeability, and the stainless steel rectangular manways can prevent medium penetration. For parts that are frequently opened, they are equipped with an anti-static device, which effectively prevents fire hazards caused by static electricity accumulation.
There is a large amount of acid and alkali, chloride ions, and microorganisms in sewage. The stainless steel rectangular manways cope well with their corrosion, while their good sealing properties prevent the spread of sewage odor. The rectangular manways with springs can be opened easily, reducing the operator’s work intensity. We support the customization of oversized rectangular manways, which is convenient for the operation of large equipment such as large dust collectors and packing towers.
The rectangular manways can resist the corrosion of the salt spray environment at sea. In addition, our stainless steel rectangular manways and spacers are absolutely watertight and can withstand seawater pressure even when the cabin is submerged. Unlike chemical plants, the cabin space is small, and the equipment is compact. The rectangular design better uses space and is easy to install.
Mold and deterioration are easy to occur when storing grain, feed, and seeds. The agricultural rectangular manways are made of stainless steel. Their surface is smooth and easy to clean, and bacteria and mold do not easily reside. Its sealing ring uses food-grade silicone, which effectively prevents external moisture, grain agglomeration, and mold. The agricultural rectangular manway has an anti-static grounding function, which avoids dust explosions caused by static electricity accumulation, and protects the safety of the warehouse.
The solid particles in the slurry and ore are usually angular and have high hardness. They are extremely abrasive for storage tanks and pipelines. The rectangular manways for mining are made of thick-walled stainless steel and dense stiffeners, which effectively resist the erosion of slurry and ore without deformation. In addition, the thick-walled rectangular manways can withstand the huge impact of high-speed transported ore when it falls.
- Certificate of Compliance
Customer Reviews
We purchased sanitary tri clamp fittings and stainless steel ferrules from OMSS for our beverage processing system. The dimensions were accurate, the polishing was clean, and the fittings connected smoothly with our existing pipes without additional adjustment. The consistent quality helped us improve installation efficiency.
EmilyOMSS supported our custom stainless steel fitting project from drawing confirmation to final production. Their engineers provided useful suggestions on material selection and processing details. The finished components matched our requirements well and performed reliably in our food equipment applications.
JohnOMSS has become one of our trusted stainless steel component suppliers. We appreciate their fast communication, clear order updates, and careful packaging. Even for customized parts with different specifications, they maintain good consistency between samples and mass production.
Sarah
The minimum size of our rectangular manways is approximately 200mm×150mm. The largest rectangular passage we have made is 2000mm×1200mm considering the processing equipment and transportation methods. If the long side of the rectangular manway exceeds 1500mm, we recommend equipping a gas spring device to assist in opening the panel.
We determine the opening size of the rectangular manway based on the specific design dimensions of your storage tank. The opening size is related to the installation method, including insert installation and panel-mounted installation.
The calculation formulas for the dimensions differ for the two installation methods. Provide the design drawings of your tank or equipment and the installation method, and we will provide opening drawings with detailed parameters.
The smoothness of opening and closing the rectangular manway panel is usually affected by the panel weight and the hinge pin. For rectangular manways with heavier panels, we recommend gas springs or spring support rods to assist during opening and closing. For the hinge pins, we suggest regularly adding lubricating oil to keep the pins rotating smoothly.
The frequency of sealing ring replacement depends on the working conditions. Typically, for chemical plants contacting highly corrosive media, we recommend checking the sealing ring every half year. For food factories contacting the general media, we recommend checking yearly. For seldom-used atmospheric water tanks, we recommend replacing them every 2-3 years.
Our basic rectangular manways do not come with a sight glass. We can create a rectangular manway with a sight glass if you need to check the inside of the tank. Depending on the working environments, we offer sight glasses made of different materials, including tempered glass, borosilicate glass, or acrylic.
In actual installation, the sealing ring is often not installed tightly due to slot design. Our rectangular manways use a dovetail slot structure, which has a wider bottom and a narrower slot opening. This design firmly locks the sealing ring in place and prevents it from falling out.
What Is A Rectangular Manway?
A rectangular manway is an access door that facilitates maintenance or feeding by operators. They are usually installed on the sides or top of tanks, containers, reactors, etc. Compared with circular manways, its straight-edge design makes it easier for personnel to enter and exit or handle large objects.
By optimizing the corner and sealing designs, it retains the advantages of the rectangular structure while achieving sealing performance comparable to that of a circular manway. It is widely used in the food, pharmaceutical, and chemical industries.
Core Technology of Rectangular Design
Precision Corner Design for Stress Dispersion
Rectangular structures tend to concentrate stress at the four corners under a pressure-rated manway. We optimize this stress-bearing structure by using large-radius arc transitions at the corners. This allows stress to be evenly distributed throughout the rectangular manways, reducing the peak stress at the four corners by more than 42%.
This arc transition design maintains structural integrity during long-term use. It prevents cracks, eliminates leakage issues, and extends the service life of the rectangular channel.
Tic-Tac-Toe Reinforcement Structure
The center of the panel in a rectangular manway tends to deform under high or negative pressure. We added a tic-tac-toe-shaped rib on the back of the rectangular manways. Its fixed position is determined through finite element analysis, which increases the bending resistance modulus by more than 300%, allowing the panel to remain flat under high pressure, negative pressure, and pressure fluctuations.
Dovetail Slot Sealing Structure
The gaskets at the four corners of the rectangular manway require special sealing due to the unique rectangular structure. We strictly design the sealing grooves of the rectangular manway. We use a dovetail structure, with the bottom width of the groove 15% larger than the opening width, to firmly lock the sealing ring.
This gasket seal for manways prevents the gasket material from being extruded from gaps or becoming uneven, which will form leakage paths.
Sanitary Polishing Treatment
Industries such as food and pharmaceuticals have strict hygiene requirements. For hygienic manways for the food tank, we design larger-radius corners and apply mirror polishing treatment to achieve an inner wall roughness of Ra≤0.4μm. This ensures that CIP cleaning can thoroughly wash the manway, preventing product spoilage and batch losses.
How to Select Sealing Rings for Rectangular Manways?
The sealing ring prevents leakage of rectangular manways. Due to the particularity of the rectangular structure, special attention should be paid to its compression resilience and extrusion resistance when selecting a sealing ring. We introduce the performance and selection points of five common sealing rings according to different working conditions.
Silicone Seals
Silicone seals are non-toxic and odorless, resistant to high temperatures, and widely used in various rectangular manways. They have excellent softness and can easily fill the gaps of rectangular manways.
The midsection of the long side of rectangular manways tends to slightly warp, while the high compression ratio(35%-45%) of silicone seals allows them to automatically adapt to unevenness or deformation caused by pressure on the long side.
EPDM Seals
Among all seal materials for rectangular manways, EPDM seals have the strongest ozone and UV resistance. They are very suitable for outdoor rectangular manways, such as water treatment and agricultural equipment. They can resist UV light, preventing cracks that could cause leaks.
NBR Seals
NBR seals have excellent oil resistance, can resist oil corrosion, and do not swell, preventing leakage caused by the increase in seal volume. NBR seals are commonly used in crude oil storage tanks and refining.
They also have outstanding mechanical strength and tear resistance, so they will not wear out after repeated opening, closing, and compression of the cover plate.
PTFE Seals
Except for molten alkali metals and high-temperature fluorine gas, PTFE seals can withstand any strong acid or alkali within pH0-14. The chemical, pharmaceutical, and agriculture industries often deal with strong acids and bases, which would quickly soften and dissolve ordinary seal materials.
Furthermore, PTFE material has a dense, hydrophobic surface, with a <5% residual amount of the medium. It does not harbor bacteria, avoiding cross-batch contamination.
Ordinary PTFE seals are slightly less elastic and cannot adapt to the deformation of rectangular channels. We offer expanded PTFE seals, which improve the elasticity of ordinary PTFE materials.
Graphite Seals
They can withstand temperatures above 600°C, far exceeding other seal materials. Therefore, graphite seals provide absolute fire safety. In the natural gas and refining industries, graphite seals in rectangular manways can prevent leaks caused by seal melting.
Graphite material almost does not creep, with a <5% thickness compression rate. This ensures stable thickness throughout the entire lifecycle of the rectangular manway.
