Screw Cap Mailers | Industrial Shipping Containers
- Material Composition: Kraft Fiberboard with Metal Screw Caps.
- Size Range: 1 3/4" x 4 1/2" to 3 1/8" x 7 3/4" internal dimensions.
- Compliance: D.O.T. compliant for non-hazardous and select hazardous shipments.
- Closure Types: Threaded Metal Cap with optional Liners.
Featured Products
| Product Description | Dimensions (D x L) | Quantity per Case |
|---|---|---|
| Screw Cap Mailers 1 3/4" x 4 1/2" | 1 3/4" x 4 1/2" | 100 |
| Screw Cap Mailers 1 3/4" x 7 1/4" | 1 3/4" x 7 1/4" | 100 |
| Screw Cap Mailers 2" x 5 1/2" | 2" x 5 1/2" | 100 |
| Screw Cap Mailers 2 1/2" x 6 1/2" | 2 1/2" x 6 1/2" | 100 |
| Screw Cap Mailers 3 1/8" x 7 3/4" | 3 1/8" x 7 3/4" | 100 |
Structural Design and Dimensions Screw cap mailers are defined by a two-piece architecture consisting of a rigid tube body and a threaded metal cap. Unlike friction-fit mailing tubes, the screw cap mechanism provides a positive mechanical lock. The internal dimensions are categorized by diameter and usable length, ensuring a precise fit for items such as glass vials, metal parts, or rolled documents. The rigid walls maintain their shape under external pressure, preventing the crushing of internal items. The standardized 100-case pack configuration supports high-volume industrial and laboratory requirements where consistent packaging dimensions are necessary for inventory management and shipping calculations.
Fiberboard and Metal Component Specifications The primary body of the mailer is manufactured from high-density, spiral-wound kraft fiberboard. This material is chosen for its high strength-to-weight ratio and resistance to puncturing. The wall thickness is engineered to meet postal and courier standards for protective packaging. The metal ends, including the threaded rim and the cap, are typically constructed from tin-plated steel. This metal provides a rigid sealing surface that resists deformation. For applications involving moisture or specific chemical exposure, the fiberboard may be treated with coatings, and the metal caps can be fitted with specialized liners to enhance the seal's barrier properties.
Compliance and Shipping Safety Screw cap mailers are engineered to meet specific Department of Transportation (D.O.T.) and United States Postal Service (USPS) regulations for the shipment of small items. When used in conjunction with secondary leak-proof containers, these mailers serve as an essential component in the "triple packaging" system required for biological or liquid samples. The structural integrity of the fiberboard and the security of the threaded closure comply with standards for impact resistance and stackability. Users must verify that the specific mailer dimensions and material specs align with the hazard class and shipping mode (air vs. ground) intended for the contents.
Cross-Sector Utility In the healthcare and pharmaceutical sectors, these containers are utilized for the distribution of diagnostic specimens and laboratory reagents. The industrial manufacturing sector employs screw cap mailers for the transport of precision-machined parts, fasteners, and cylindrical tools that require protection from surface abrasion. In environmental testing, they serve as protective outers for soil or water sample containers. Furthermore, the agricultural industry uses these mailers for the secure transport of seed samples and soil additives. The versatility of the size range allows for the standardization of shipping protocols across different departments within an organization.
Technical Factors for Procurement Selecting the appropriate screw cap mailer requires an analysis of the item's physical dimensions and the environmental stresses of the transit route. The internal diameter must allow for sufficient clearance if secondary cushioning materials, such as bubble wrap or foam sleeves, are required. Compatibility between the metal cap and the contents is critical; if the contents are corrosive, an internal barrier or liner is necessary to prevent oxidation of the steel cap. Additionally, the total weight of the loaded mailer must be compared against the burst strength of the fiberboard to ensure the bottom metal seal remains intact throughout the logistics chain.
