Still, the grid frame is the rigid cage that holds the crimped ribbon or expanded metal flame arrester element inside a storage tank breather vent or end-of-line flame arrester, setting the element gap and the sealing face. Ningbo Ruican investment casts the frame and machines the housing seat, bolt circle and element retaining faces in house, which fixes the two issues that cause re-test failures: distorted element gaps that let a flame front pass, and sealing faces that leak during the endurance and corrosion testing regimes.
Specifications
| Parameter | Specification |
|---|---|
| Casting process | Silica sol lost wax investment casting; water glass process for frames above 25 kg |
| Material options | ASTM A351 CF8M, CF8, CF3M stainless; A356-T6 aluminium; ASTM A216 WCB carbon steel; C95800 aluminium bronze |
| Dimensional tolerance (ISO 8062-3 CT grade) | CT5 to CT7 as cast; element seating face flatness within 0.05 mm; bolt circle to ISO 2768-m or drawing |
| Machining | CNC milling and turning of housing seat, element retaining face, bolt circle and threaded connections to NPT, BSP or flange drillings |
| Surface finish (Ra) | As-cast Ra 6.3 um; machined sealing faces Ra 1.6-3.2 um; passivated or electropolished Ra 0.8 um optional |
| Pressure testing | Hydrostatic or pneumatic leak test of the assembled frame and housing to customer procedure; element gap verified by gauge and optical check |
| Weight range | 0.6 kg to 38 kg per frame |
| Typical lead time | 25 to 35 days for tooling and samples; 30 to 45 days for production after sample approval |
Scope and options
Key features
- Element seating face machined flat within 0.05 mm, holding the arrester ribbon gap uniform so the flame quenching path is never bypassed.
- Cast lattice ribs and cross members give high stiffness at low mass, protecting the element from vibration and water hammer in tank breathing cycles.
- Corrosion resistant CF8M and CF3M grades for coastal, chemical and offshore tank farms, with A356-T6 aluminium for weight-critical vent stacks.
- Bolt circle and flange drilling machined to your pattern, so the frame drops into existing vent housings without modification.
- Drain, pressure tapping and earth bonding bosses cast in and machined to drawing, reducing fabrication steps on the assembled vent.
- Smooth cast surfaces on the gas path lower breathing pressure drop and reduce ice and product build-up in cold or waxy service.
Applications
- Storage tank breather vents on crude, fuel oil and diesel tank farms.
- End-of-line and in-line flame arresters on chemical and solvent storage tanks.
- Vapour recovery and low pressure vent stacks in refineries and terminals.
- Marine cargo tank vent systems and inert gas line flame arresters.
- Biogas, landfill gas and wastewater digester gas vent arresters.
- Food, beverage and edible oil storage tanks needing polished stainless vent assemblies.
Quality & compliance
Inspection and documentation
Flame arrester grid frames are produced under IATF 16949 control with capability monitoring of element seating face flatness and rib spacing, since these define the flame quenching performance of the finished arrester. EN 10204 3.1 material certification is standard and 3.2 witnessed certification can be arranged. Leak testing of the frame and housing assembly, dimensional reporting and element gap verification are performed to your procedure and archived against batch records. Non-destructive examination including dye penetrant inspection per ASTM E165, radiography of rib junctions and positive material identification by XRF are available on request, along with PPAP and first article inspection. Also, Ningbo Ruican does not hold or claim ISO 16852, ATEX or CE certification as a company certificate; we build to your specified standard and supply the evidence package your own certification body requires.
FAQ
Can you hold the element gap tolerance?
Yes. The element seating face is machined flat to within 0.05 mm and the retaining shoulders are held to drawing tolerance, so the ribbon gap cannot open under clamping load. The gap is then verified by gauge and optical measurement on every sample and at an agreed frequency during production, with the results recorded on the dimensional report.
Which materials suit coastal or chemical tank farms?
Generally, CF8M and CF3M stainless are the usual choice for chloride and chemical exposure, C95800 aluminium bronze suits marine splash zones, and A356-T6 aluminium is used where vent stack weight matters. Send us your gas group, product vapour and site atmosphere, and our metallurgist will confirm the grade, the corrosion allowance and the required surface protection before tooling begins.
Do you supply the frame only or the complete assembly?
In general, we typically supply the cast and machined frame. We can also source or assemble the element, gaskets and housing to deliver a complete breather vent sub-assembly. Also, tell us which scope fits your production line and we will quote accordingly.
What testing can you perform before shipment?
We carry out hydrostatic or pneumatic leak testing of the assembled frame and housing, full dimensional inspection with a written report, element gap verification and surface finish measurement against your specified Ra. Dye penetrant inspection per ASTM E165 and radiographic examination of rib junctions are available to your acceptance criteria and sampling plan.
What sizes of frame can you cast?
We cast frames from 0.6 kg to 38 kg covering DN50 to DN300 vent connections, in silica sol for precision-critical sizes and water glass for larger frames. Send your drawing and we will confirm the process route and tooling cost.
CTA
Send your flame arrester grid frame drawing, gas group, material and annual requirement to Ningbo Ruican and receive a cast and machined quotation with a tooling proposal. Contact Wendy She at sales@cnsandcasting.com or WhatsApp +86-13777124360, or review more projects at cnsandcasting.com.
