A bolt connection is provided for connecting two flanges. The bolt connection includes a threaded bar extending through a hole of a first flange and a hole of a second flange, the first flange abutting the second flange; an anti-fatigue sleeve; and a nut. The anti-fatigue sleeve is disposed on the threaded bar on the side of the first flange between the nut and the first flange, the nut is configured to be screwed onto the threaded bar and is configured to press the anti-fatigue sleeve against the first flange to fasten the first flange and the second flange together.

A bolt connection is provided for connecting two flanges. The bolt connection includes a threaded bar extending through a hole of a first flange and a hole of a second flange, the first flange abutting the second flange; an anti-fatigue sleeve; and a nut. The anti-fatigue sleeve is disposed on the threaded bar on the side of the first flange between the nut and the first flange, the nut is configured to be screwed onto the threaded bar and is configured to press the anti-fatigue sleeve against the first flange to fasten the first flange and the second flange together.

A bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to an embodiment of the present invention consists of, in mass %, C: 0.32 to 0.39%, Si: 0.15% or less, Mn: 0.40 to 0.65%, P: 0.020% or less, S: 0.020% or less, Cr: 0.85 to 1.25%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.050%, B: 0.0010 to 0.0030%, N: 0.0015 to 0.0080%, O: 0.0015% or less, Mo: 0 to 0.05%, V: 0 to 0.05%, Cu: 0 to 0.50%, Ni: 0 to 0.30%, and Nb: 0 to 0.05%, with the balance being Fe and impurities. The bolt satisfies Formula (1) and Formula (2), and has a tensile strength of 1000 to 1300 MPa and satisfies Formula (3).
4.910C+Si+2Mn+Cr+4Mo+5V6.1(1)
Mn/Cr0.55(2)
[dissolved Cr]/Cr0.70(3)

A bolt is provided that has high strength and excellent hydrogen embrittlement resistance characteristics. A bolt according to an embodiment of the present invention consists of, in mass %, C: 0.32 to 0.39%, Si: 0.15% or less, Mn: 0.40 to 0.65%, P: 0.020% or less, S: 0.020% or less, Cr: 0.85 to 1.25%, Al: 0.005 to 0.060%, Ti: 0.010 to 0.050%, B: 0.0010 to 0.0030%, N: 0.0015 to 0.0080%, O: 0.0015% or less, Mo: 0 to 0.05%, V: 0 to 0.05%, Cu: 0 to 0.50%, Ni: 0 to 0.30%, and Nb: 0 to 0.05%, with the balance being Fe and impurities. The bolt satisfies Formula (1) and Formula (2), and has a tensile strength of 1000 to 1300 MPa and satisfies Formula (3).
4.910C+Si+2Mn+Cr+4Mo+5V6.1(1)
Mn/Cr0.55(2)
[dissolved Cr]/Cr0.70(3)

A fluid end having its fluid flow bores sealed without threading a retaining nut into the walls of each bore. The fluid ends may be assembled using a plurality of different kits that each comprise a fluid end body, a component, a retainer element, and a fastening system. The retainer element holds the component within each of the bores formed in the fluid end body and the fastening system secures the retainer element to the body. The fastening system comprises a plurality of externally threaded studs, washers and nuts in some embodiments. In other embodiments, the fastening system comprises a plurality of screws.

A high-strength screw (1) includes a head (2) and a threaded portion (5) including a thread (6) and a thread end (9) facing away from the head (2) in an axial direction. The threaded portion (5) includes an unhardened portion (12) starting at the thread end (9) and extending in an axial direction. The unhardened portion (12) has a hardness being reduced compared to an axial middle portion (11) of the threaded portion (5).

A high-strength screw (1) includes a head (2) and a threaded portion (5) including a thread (6) and a thread end (9) facing away from the head (2) in an axial direction. The threaded portion (5) includes an unhardened portion (12) starting at the thread end (9) and extending in an axial direction. The unhardened portion (12) has a hardness being reduced compared to an axial middle portion (11) of the threaded portion (5).

A fastener including a bolt having an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, the bolt thread including a bolt pitch. The fastener includes a nut having a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt. The nut thread includes a nut pitch and a hardness that changes gradationally between the first and second ends of the nut. The bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.

A fastener including a bolt having an elongated shank having a first end, a second end opposite the first end, and a threaded portion having an external bolt thread, the bolt thread including a bolt pitch. The fastener includes a nut having a first end, a second end opposite the first end of the nut, and an internal nut thread extending between the first and second ends of the nut and adapted to engage threadedly the bolt thread of the bolt. The nut thread includes a nut pitch and a hardness that changes gradationally between the first and second ends of the nut. The bolt pitch of the bolt thread of the bolt is mismatched with the nut pitch of the nut thread of the nut.

A micro fluid filtration system (100) preferably for increasing the concentration of components contained in a fluid sample has a fluid circuitry (1). The fluid circuitry (1) comprises the following elements: A tangential flow filtration element (7) capable for separating the fluid sample into a retentate stream and a permeate stream upon passage of the fluid, an element for pumping (3) for creating and driving a fluid flow through the fluid circuitry (1) and at least one element for obtaining information about the properties of the fluid sample within the circuitry. The circuitry further comprises a plurality of conduits (24) connecting the elements of the fluid circuitry (1) through which a fluid stream of the fluid sample is conducted. The circuitry (1) has a minimal working volume of at most 5 ml, which is the minimal fluid volume retained in the elements and the conduits (24) of the circuitry (1) such that the fluid can be recirculated in the circuitry (1) without pumping air through the circuitry (1). An integrated microfluidic element (20) of the circuitry (1) contains the functionality of at least two elements of the group of elements of the circuitry (1).