diff --git a/include/components/CoaxialJunction1Phase.h b/include/components/CoaxialJunction1Phase.h
new file mode 100644
index 0000000..8c8e8be
--- /dev/null
+++ b/include/components/CoaxialJunction1Phase.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "Component.h"
+#include "InputParameters.h"
+
+class CoaxialJunction1Phase : public Component {
+public:
+  static InputParameters validParams();
+
+  CoaxialJunction1Phase(const InputParameters &params);
+
+protected:
+  /// Connects the same solid region of two coaxial pipes
+  void ConnectSolidRegion(const std::string &region_name,
+                          const ComponentName &component1,
+                          const ComponentName &component2);
+
+  /// Connects the same flow region of two coaxial pipes
+  void ConnectFlowRegion(const std::string &region_name,
+                         const ComponentName &component1,
+                         const ComponentName &component2);
+};
\ No newline at end of file
diff --git a/include/components/CoaxialPipe1Phase.h b/include/components/CoaxialPipe1Phase.h
index 97785b8..4ceb4b2 100644
--- a/include/components/CoaxialPipe1Phase.h
+++ b/include/components/CoaxialPipe1Phase.h
@@ -1,4 +1,6 @@
-#include <Component1D.h>
+#pragma once
+
+#include <Component.h>
 #include <FlowChannel1Phase.h>
 #include <InputParameters.h>
 
diff --git a/src/components/CoaxialJunction1Phase.C b/src/components/CoaxialJunction1Phase.C
new file mode 100644
index 0000000..8a02f1a
--- /dev/null
+++ b/src/components/CoaxialJunction1Phase.C
@@ -0,0 +1,131 @@
+#include "CoaxialJunction1Phase.h"
+#include "Component.h"
+#include "InputParameters.h"
+#include "MooseTypes.h"
+#include "Registry.h"
+
+registerMooseObject("ProteusApp", CoaxialJunction1Phase);
+
+namespace {
+// Splits component name into component and boundary pair and checks validity
+inline std::pair<std::string, std::string>
+getComponentAndBoundary(const ComponentName &component) {
+  auto it = component.rfind(":");
+  if (it == component.size())
+    mooseError("No boundary specified. 'coaxial_connections' must be specified "
+               "as <coaxial>:<boundary>.");
+
+  auto comp = component.substr(0, it);
+  auto boundary = component.substr(it + 1);
+
+  if (!(boundary == "in" || boundary == "out"))
+    mooseError("Boundary must be 'in' or 'out', not '", boundary, "'.");
+
+  return {comp, boundary};
+}
+} // namespace
+
+InputParameters CoaxialJunction1Phase::validParams() {
+  auto params = Component::validParams();
+  params.addRequiredParam<std::vector<ComponentName>>(
+      "coaxial_connections", "Coaxial pipes boundaries to connect. "
+                             "<name>:in indicates start of the pipe, "
+                             "<name>:out indicates the end of the pipe.");
+
+  // Passed to 2D coupler
+  params.addRequiredParam<FunctionName>("tube_htc",
+                                        "HTC used for coupling tube regions.");
+  params.addRequiredParam<FunctionName>("shell_htc",
+                                        "HTC used for coupling shell regions.");
+
+  // Allows other componenets such as pumps to be inserted instead
+  params.addParam<bool>("connect_inner", true,
+                        "Whether to connect inner pipe.");
+  params.addParam<bool>("connect_outer", true,
+                        "Whether to connect the outer annulus.");
+
+  params.addParam<bool>("connect_tube", true,
+                        "Whether to connect the solid tube regions.");
+  params.addParam<bool>("connect_shell", true,
+                        "Whether to connect the solid shell regions.");
+
+  return params;
+}
+
+CoaxialJunction1Phase::CoaxialJunction1Phase(const InputParameters &params)
+    : Component(params) {
+
+  auto coaxials = params.get<std::vector<ComponentName>>("coaxial_connections");
+
+  if (coaxials.size() != 2)
+    mooseError("'coaxial_connections' must have size 2.");
+
+  if (getParam<bool>("connect_tube")) {
+    ConnectSolidRegion("tube", coaxials[0], coaxials[1]);
+  }
+
+  if (getParam<bool>("connect_shell")) {
+    ConnectSolidRegion("shell", coaxials[0], coaxials[1]);
+  }
+
+  if (params.get<bool>("connect_inner")) {
+    ConnectFlowRegion("inner", coaxials[0], coaxials[1]);
+  }
+  if (params.get<bool>("connect_outer")) {
+    ConnectFlowRegion("outer", coaxials[0], coaxials[1]);
+  }
+}
+
+void CoaxialJunction1Phase::ConnectSolidRegion(
+    const std::string &region_name, const ComponentName &component1,
+    const ComponentName &component2) {
+  auto comp_boundary1 = getComponentAndBoundary(component1);
+  auto comp_boundary2 = getComponentAndBoundary(component2);
+
+  const std::string class_name = "HeatStructure2DCoupler";
+  auto params = _factory.getValidParams(class_name);
+  params.set<THMProblem *>("_thm_problem") = &getTHMProblem();
+
+  // The ends of the solid regions are called start and end rather than in and
+  // out
+  auto boundary1 = (comp_boundary1.second == "in") ? "start" : "end";
+  auto boundary2 = (comp_boundary2.second == "in") ? "start" : "end";
+
+  params.set<std::string>("primary_heat_structure") =
+      comp_boundary1.first + "/" + region_name;
+  params.set<BoundaryName>("primary_boundary") =
+      comp_boundary1.first + "/" + region_name + ":" + boundary1;
+
+  params.set<std::string>("secondary_heat_structure") =
+      comp_boundary2.first + "/" + region_name;
+  params.set<BoundaryName>("secondary_boundary") =
+      comp_boundary2.first + "/" + region_name + ":" + boundary2;
+
+  params.set<FunctionName>("heat_transfer_coefficient") =
+      parameters().get<FunctionName>(region_name + "_htc");
+
+  getTHMProblem().addComponent(class_name,
+                               name() + "/" + region_name + "_coupler", params);
+}
+
+void CoaxialJunction1Phase::ConnectFlowRegion(const std::string &region_name,
+                                              const ComponentName &component1,
+                                              const ComponentName &component2) {
+  auto comp_boundary1 = getComponentAndBoundary(component1);
+  auto comp_boundary2 = getComponentAndBoundary(component2);
+
+  // In the future, we could create a component to account for form
+  // loss due to geometry changes
+  const std::string class_name = "JunctionOneToOne1Phase";
+  auto params = _factory.getValidParams(class_name);
+  params.set<THMProblem *>("_thm_problem") = &getTHMProblem();
+
+  std::vector<BoundaryName> connections = {
+      comp_boundary1.first + "/" + region_name + ":" + comp_boundary1.second,
+      comp_boundary2.first + "/" + region_name + ":" + comp_boundary2.second,
+  };
+  params.set<std::vector<BoundaryName>>("connections") = connections;
+
+  getTHMProblem().addComponent(
+      class_name, name() + "/" + region_name + "_junction", params);
+}
diff --git a/src/components/CoaxialPipe1Phase.C b/src/components/CoaxialPipe1Phase.C
index bf22a5b..0afc3fe 100644
--- a/src/components/CoaxialPipe1Phase.C
+++ b/src/components/CoaxialPipe1Phase.C
@@ -130,8 +130,10 @@ InputParameters CoaxialPipe1Phase::validParams() {
   params.addParam<FunctionName>("initial_p", "Global pressure initialisation");
   params.addParam<FunctionName>("initial_vel",
                                 "Global velocity initialisation");
-  params.addParamNamesToGroup("fp closures initial_T initial_p initial_vel",
-                              "global");
+  params.addParam<RealVectorValue>(
+      "gravity_vector", RealVectorValue{0, 0, -9.81}, "Gravity vector");
+  params.addParamNamesToGroup(
+      "fp closures initial_T initial_p initial_vel gravity_vector", "global");
 
   return params;
 }
@@ -175,6 +177,10 @@ void CoaxialPipe1Phase::AddInnerPipe(const InputParameters &params) {
       params.get<RealVectorValue>("orientation");
   pipe_params.set<std::vector<Real>>("length") =
       params.get<std::vector<Real>>("length");
+  pipe_params.set<std::vector<std::string>>("axial_region_names") =
+      params.get<std::vector<std::string>>("axial_region_names");
+  pipe_params.set<RealVectorValue>("gravity_vector") =
+      params.get<RealVectorValue>("gravity_vector");
 
   Real radius = params.get<Real>("tube_inner_radius");
 
@@ -214,6 +220,10 @@ void CoaxialPipe1Phase::AddOuterAnnulus(const InputParameters &params) {
       params.get<RealVectorValue>("orientation");
   pipe_params.set<std::vector<Real>>("length") =
       params.get<std::vector<Real>>("length");
+  pipe_params.set<std::vector<std::string>>("axial_region_names") =
+      params.get<std::vector<std::string>>("axial_region_names");
+  pipe_params.set<RealVectorValue>("gravity_vector") =
+      params.get<RealVectorValue>("gravity_vector");
 
   Real tube_radius = params.get<Real>("tube_inner_radius");
   auto tube_widths = params.get<std::vector<Real>>("tube_widths");
@@ -264,6 +274,8 @@ void CoaxialPipe1Phase::AddSolidTube(const InputParameters &params) {
       params.get<RealVectorValue>("orientation");
   tube_params.set<std::vector<Real>>("length") =
       params.get<std::vector<Real>>("length");
+  tube_params.set<std::vector<std::string>>("axial_region_names") =
+      params.get<std::vector<std::string>>("axial_region_names");
 
   copyParamFromParamWithGlobal<FunctionName>("initial_T", "tube_initial_T",
                                              "initial_T", tube_params, params);
@@ -297,6 +309,8 @@ void CoaxialPipe1Phase::AddSolidShell(const InputParameters &params) {
       params.get<RealVectorValue>("orientation");
   tube_params.set<std::vector<Real>>("length") =
       params.get<std::vector<Real>>("length");
+  tube_params.set<std::vector<std::string>>("axial_region_names") =
+      params.get<std::vector<std::string>>("axial_region_names");
 
   copyParamFromParamWithGlobal<FunctionName>("initial_T", "shell_initial_T",
                                              "initial_T", tube_params, params);
diff --git a/test/tests/components/coaxial_junction/junction_fluid.i b/test/tests/components/coaxial_junction/junction_fluid.i
new file mode 100644
index 0000000..13a7154
--- /dev/null
+++ b/test/tests/components/coaxial_junction/junction_fluid.i
@@ -0,0 +1,210 @@
+# Energy balance test
+# ===================
+#
+# Apply 10 kW/m^2 to outer surface of the
+# shell and check the increase in temperature at the fluid outlets
+
+T = 300
+press = 1e5 # operating pressure
+
+L = 1 # length of pipe
+
+[GlobalParams]
+  initial_p = ${press}
+  closures = thm_closures
+  fp=fluid
+  gravity_vector = '0 0 0'
+[]
+
+[FluidProperties]
+  [fluid] # mimic of water
+    type = SimpleFluidProperties
+    cv = 4000
+  []
+  [fluid2] # mimic of water
+    type = SimpleFluidProperties
+    cv = 2000
+  []
+[]
+
+[SolidProperties]
+  [adamantium] # fake solid material that ensures solid heats quickly
+    type = ThermalFunctionSolidProperties
+    cp = 1
+    k = 1
+    rho = 1
+  []
+  [ebony] # fake solid material that ensures solid heats quickly
+    type = ThermalFunctionSolidProperties
+    cp = 1
+    k = 4
+    rho = 16
+  []
+[]
+
+[Closures] # defines friction factors and heat transfer coefficients
+  [thm_closures]
+    type = Closures1PhaseTHM # default Churchill friction factor, DB HTC
+  []
+[]
+
+[Components]
+  [inlet_inner]
+      type = InletMassFlowRateTemperature1Phase
+      T = ${T}
+      m_dot = 1.
+      input = coaxial1/inner:in
+  []
+  [inlet_outer]
+      type = InletMassFlowRateTemperature1Phase
+      T = ${T}
+      m_dot = 1.
+      input = coaxial2/outer:out
+  []
+  [coaxial1]
+    type = CoaxialPipe1Phase
+    length = '${L}'
+    n_elems = '10'
+    orientation = '1 0 0'
+    position = '${fparse -L} 0 0'
+    shell_inner_radius = 0.075
+    shell_materials = 'adamantium'
+    shell_n_elems = '1'
+    shell_names = 'shell'
+    shell_widths = '0.025'
+    shell_T_ref = '${T}'
+    tube_T_ref = ${T}
+    tube_inner_radius = 0.025
+    tube_materials = 'adamantium'
+    tube_n_elems = '1'
+    tube_names = 'tube'
+    tube_widths = '0.025'
+    inner_initial_vel = 0.
+    outer_initial_vel = 0.
+    initial_T = ${T}
+    inner_tube_Hw = 0.
+    outer_tube_Hw = 0.
+    outer_shell_Hw = 0.
+  []
+  [jct]
+    type = CoaxialJunction1Phase
+    coaxial_connections = 'coaxial1:out coaxial2:in'
+    shell_htc = 1e10
+    tube_htc = 1e10
+  []
+  [coaxial2]
+    type = CoaxialPipe1Phase
+    length = '${L}'
+    n_elems = '10'
+    orientation = '1 0 0'
+    position = '0 0 0'
+    shell_inner_radius = 0.075
+    shell_materials = 'ebony'
+    shell_n_elems = '1'
+    shell_names = 'shell'
+    shell_widths = '0.025'
+    shell_T_ref = '${T}'
+    tube_T_ref = ${T}
+    tube_inner_radius = 0.025
+    tube_materials = 'ebony'
+    tube_n_elems = '1'
+    tube_names = 'tube'
+    tube_widths = '0.025'
+    inner_initial_vel = 0.
+    outer_initial_vel = 0.
+    initial_T = ${T}
+    inner_tube_Hw = 0.
+    outer_tube_Hw = 0.
+    outer_shell_Hw = 0.
+  []
+  [outlet_outer]
+    type =Outlet1Phase
+    input = coaxial1/outer:in
+    p = ${press}
+  []
+  [outlet_inner]
+      type =Outlet1Phase
+      input = coaxial2/inner:out
+      p = ${press}
+  []
+  [tube_start1]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T}
+    boundary = 'coaxial1/tube:start'
+    hs = coaxial1/tube
+  []
+  [shell_start1]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T}
+    boundary = 'coaxial1/shell:start'
+    hs = coaxial1/tube
+  []
+  [tube_end2]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T}
+    boundary = 'coaxial2/tube:end'
+    hs = coaxial1/tube
+  []
+  [shell_end2]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T}
+    boundary = 'coaxial2/shell:end'
+    hs = coaxial2/tube
+  []
+
+[]
+
+
+[Postprocessors]
+  [mdot_inner]
+    type = ADFlowBoundaryFlux1Phase
+    boundary = outlet_inner
+    equation = mass
+  []
+  [mdot_outer]
+    type = ADFlowBoundaryFlux1Phase
+    boundary = outlet_outer
+    equation = mass
+  []
+
+[]
+
+[Preconditioning]
+  [pc]
+    type = SMP
+    full = true
+  []
+[]
+
+[Executioner]
+  type = Transient
+  start_time = 0
+
+  dt = 1.
+  end_time = 10
+
+  line_search = basic
+  solve_type = NEWTON
+
+  petsc_options_iname = '-pc_type'
+  petsc_options_value = 'lu'
+
+  nl_rel_tol = 1e-4
+  nl_abs_tol = 1e-6
+  nl_max_its = 25
+  automatic_scaling = true
+  steady_state_detection = true
+  # steady_state_tolerance = 2e-7
+[]
+
+[Outputs]
+  exodus = true
+  csv = true
+  [console]
+    type = Console
+    max_rows = 1
+    execute_postprocessors_on = final
+    outlier_variable_norms = false
+  []
+  print_linear_residuals = false
+[]
diff --git a/test/tests/components/coaxial_junction/junction_solid.i b/test/tests/components/coaxial_junction/junction_solid.i
new file mode 100644
index 0000000..6bc34f0
--- /dev/null
+++ b/test/tests/components/coaxial_junction/junction_solid.i
@@ -0,0 +1,222 @@
+# Energy balance test
+# ===================
+#
+# Apply 10 kW/m^2 to outer surface of the
+# shell and check the increase in temperature at the fluid outlets
+
+T_1 = 301
+T_2 = 300
+press = 1e5 # operating pressure
+
+L = 1 # length of pipe
+
+[GlobalParams]
+  initial_p = ${press}
+  closures = thm_closures
+  fp=fluid
+  gravity_vector = '0 0 0'
+[]
+
+[FluidProperties]
+  [fluid] # mimic of water
+    type = SimpleFluidProperties
+    cv = 4000
+  []
+  [fluid2] # mimic of water
+    type = SimpleFluidProperties
+    cv = 2000
+  []
+[]
+
+[SolidProperties]
+  [adamantium] # fake solid material that ensures solid heats quickly
+    type = ThermalFunctionSolidProperties
+    cp = 1
+    k = 1
+    rho = 1
+  []
+  [ebony] # fake solid material that ensures solid heats quickly
+    type = ThermalFunctionSolidProperties
+    cp = 1
+    k = 4
+    rho = 16
+  []
+[]
+
+[Closures] # defines friction factors and heat transfer coefficients
+  [thm_closures]
+    type = Closures1PhaseTHM # default Churchill friction factor, DB HTC
+  []
+[]
+
+[Components]
+  [inlet_inner]
+      type = InletMassFlowRateTemperature1Phase
+      T = ${fparse 0.5*(T_1 + T_2)}
+      m_dot = 0.
+      input = coaxial1/inner:in
+  []
+  [inlet_outer]
+      type = InletMassFlowRateTemperature1Phase
+      T = ${fparse 0.5*(T_1 + T_2)}
+      m_dot = 0.
+      input = coaxial2/outer:out
+  []
+  [coaxial1]
+    type = CoaxialPipe1Phase
+    length = '${fparse L/3} ${fparse L/3} ${fparse L/3}'
+    axial_region_names = 'part1 part2 part3'
+    n_elems = '8 16 32'
+    orientation = '1 0 0'
+    position = '${fparse -L} 0 0'
+    shell_inner_radius = 0.075
+    shell_materials = 'adamantium'
+    shell_n_elems = '1'
+    shell_names = 'shell'
+    shell_widths = '0.025'
+    shell_T_ref = '${T_1}'
+    tube_T_ref = ${T_1}
+    tube_inner_radius = 0.025
+    tube_materials = 'adamantium'
+    tube_n_elems = '1'
+    tube_names = 'tube'
+    tube_widths = '0.025'
+    inner_initial_vel = 0.
+    outer_initial_vel = 0.
+    initial_T = ${T_1}
+    inner_tube_Hw = 0.
+    outer_tube_Hw = 0.
+    outer_shell_Hw = 0.
+  []
+  [jct]
+    type = CoaxialJunction1Phase
+    coaxial_connections = 'coaxial1:out coaxial2:in'
+    shell_htc = 1e10
+    tube_htc = 1e10
+  []
+  [coaxial2]
+    type = CoaxialPipe1Phase
+    length = '${fparse L/3} ${fparse L/3} ${fparse L/3}'
+    axial_region_names = 'part1 part2 part3'
+    n_elems = '32 16 8'
+    orientation = '1 0 0'
+    position = '0 0 0'
+    shell_inner_radius = 0.075
+    shell_materials = 'ebony'
+    shell_n_elems = '1'
+    shell_names = 'shell'
+    shell_widths = '0.025'
+    shell_T_ref = '${T_2}'
+    tube_T_ref = ${T_2}
+    tube_inner_radius = 0.025
+    tube_materials = 'ebony'
+    tube_n_elems = '1'
+    tube_names = 'tube'
+    tube_widths = '0.025'
+    inner_initial_vel = 0.
+    outer_initial_vel = 0.
+    initial_T = ${T_2}
+    inner_tube_Hw = 0.
+    outer_tube_Hw = 0.
+    outer_shell_Hw = 0.
+  []
+  [outlet_outer]
+    type =Outlet1Phase
+    input = coaxial1/outer:in
+    p = ${press}
+  []
+  [outlet_inner]
+      type =Outlet1Phase
+      input = coaxial2/inner:out
+      p = ${press}
+  []
+  [tube_start1]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_1}
+    boundary = 'coaxial1/tube:start'
+    hs = coaxial1/tube
+  []
+  [shell_start1]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_1}
+    boundary = 'coaxial1/shell:start'
+    hs = coaxial1/tube
+  []
+  [tube_end2]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_2}
+    boundary = 'coaxial2/tube:end'
+    hs = coaxial1/tube
+  []
+  [shell_end2]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_2}
+    boundary = 'coaxial2/shell:end'
+    hs = coaxial2/tube
+  []
+
+[]
+
+
+[Postprocessors]
+  [T_shell_out1]
+    type = SideAverageValue
+    boundary = coaxial1/shell:end
+    variable = T_solid
+  []
+  [T_shell_in2]
+    type = SideAverageValue
+    boundary = coaxial2/shell:start
+    variable = T_solid
+  []
+  [T_tube_out1]
+    type = SideAverageValue
+    boundary = coaxial1/tube:end
+    variable = T_solid
+  []
+  [T_tube_in2]
+    type = SideAverageValue
+    boundary = coaxial2/tube:start
+    variable = T_solid
+  []
+[]
+
+[Preconditioning]
+  [pc]
+    type = SMP
+    full = true
+  []
+[]
+
+[Executioner]
+  type = Transient
+  start_time = 0
+
+  dt = 0.0001
+  end_time = 0.01
+
+  line_search = basic
+  solve_type = NEWTON
+
+  petsc_options_iname = '-pc_type'
+  petsc_options_value = 'lu'
+
+  nl_rel_tol = 1e-4
+  nl_abs_tol = 1e-6
+  nl_max_its = 25
+  automatic_scaling = true
+  steady_state_detection = true
+  # steady_state_tolerance = 2e-7
+[]
+
+[Outputs]
+  exodus = true
+  csv = true
+  [console]
+    type = Console
+    max_rows = 1
+    execute_postprocessors_on = final
+    outlier_variable_norms = false
+  []
+  print_linear_residuals = false
+[]
diff --git a/test/tests/components/coaxial_junction/junction_solid_expand.i b/test/tests/components/coaxial_junction/junction_solid_expand.i
new file mode 100644
index 0000000..9b4aee7
--- /dev/null
+++ b/test/tests/components/coaxial_junction/junction_solid_expand.i
@@ -0,0 +1,222 @@
+# Energy balance test
+# ===================
+#
+# Apply 10 kW/m^2 to outer surface of the
+# shell and check the increase in temperature at the fluid outlets
+
+T_1 = 301
+T_2 = 300
+press = 1e5 # operating pressure
+
+L = 1 # length of pipe
+
+[GlobalParams]
+  initial_p = ${press}
+  closures = thm_closures
+  fp=fluid
+  gravity_vector = '0 0 0'
+[]
+
+[FluidProperties]
+  [fluid] # mimic of water
+    type = SimpleFluidProperties
+    cv = 4000
+  []
+  [fluid2] # mimic of water
+    type = SimpleFluidProperties
+    cv = 2000
+  []
+[]
+
+[SolidProperties]
+  [adamantium] # fake solid material that ensures solid heats quickly
+    type = ThermalFunctionSolidProperties
+    cp = 1
+    k = 1
+    rho = 1
+  []
+  [ebony] # fake solid material that ensures solid heats quickly
+    type = ThermalFunctionSolidProperties
+    cp = 1
+    k = 4
+    rho = 16
+  []
+[]
+
+[Closures] # defines friction factors and heat transfer coefficients
+  [thm_closures]
+    type = Closures1PhaseTHM # default Churchill friction factor, DB HTC
+  []
+[]
+
+[Components]
+  [inlet_inner]
+      type = InletMassFlowRateTemperature1Phase
+      T = ${fparse 0.5*(T_1 + T_2)}
+      m_dot = 0.
+      input = coaxial1/inner:in
+  []
+  [inlet_outer]
+      type = InletMassFlowRateTemperature1Phase
+      T = ${fparse 0.5*(T_1 + T_2)}
+      m_dot = 0.
+      input = coaxial2/outer:out
+  []
+  [coaxial1]
+    type = CoaxialPipe1Phase
+    length = '${fparse L/3} ${fparse L/3} ${fparse L/3}'
+    axial_region_names = 'part1 part2 part3'
+    n_elems = '8 16 32'
+    orientation = '1 0 0'
+    position = '${fparse -L} 0 0'
+    shell_inner_radius = 0.075
+    shell_materials = 'adamantium'
+    shell_n_elems = '2'
+    shell_names = 'shell'
+    shell_widths = '0.025'
+    shell_T_ref = '${T_1}'
+    tube_T_ref = ${T_1}
+    tube_inner_radius = 0.025
+    tube_materials = 'adamantium'
+    tube_n_elems = '1'
+    tube_names = 'tube'
+    tube_widths = '0.025'
+    inner_initial_vel = 0.
+    outer_initial_vel = 0.
+    initial_T = ${T_1}
+    inner_tube_Hw = 0.
+    outer_tube_Hw = 0.
+    outer_shell_Hw = 0.
+  []
+  [jct]
+    type = CoaxialJunction1Phase
+    coaxial_connections = 'coaxial1:out coaxial2:in'
+    shell_htc = 1e10
+    tube_htc = 1e10
+  []
+  [coaxial2]
+    type = CoaxialPipe1Phase
+    length = '${fparse L/3} ${fparse L/3} ${fparse L/3}'
+    axial_region_names = 'part1 part2 part3'
+    n_elems = '32 16 8'
+    orientation = '1 0 0'
+    position = '0 0 0'
+    shell_inner_radius = 0.08
+    shell_materials = 'ebony'
+    shell_n_elems = '2'
+    shell_names = 'shell'
+    shell_widths = '0.025'
+    shell_T_ref = '${T_2}'
+    tube_T_ref = ${T_2}
+    tube_inner_radius = 0.025
+    tube_materials = 'ebony'
+    tube_n_elems = '1'
+    tube_names = 'tube'
+    tube_widths = '0.025'
+    inner_initial_vel = 0.
+    outer_initial_vel = 0.
+    initial_T = ${T_2}
+    inner_tube_Hw = 0.
+    outer_tube_Hw = 0.
+    outer_shell_Hw = 0.
+  []
+  [outlet_outer]
+    type =Outlet1Phase
+    input = coaxial1/outer:in
+    p = ${press}
+  []
+  [outlet_inner]
+      type =Outlet1Phase
+      input = coaxial2/inner:out
+      p = ${press}
+  []
+  [tube_start1]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_1}
+    boundary = 'coaxial1/tube:start'
+    hs = coaxial1/tube
+  []
+  [shell_start1]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_1}
+    boundary = 'coaxial1/shell:start'
+    hs = coaxial1/tube
+  []
+  [tube_end2]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_2}
+    boundary = 'coaxial2/tube:end'
+    hs = coaxial1/tube
+  []
+  [shell_end2]
+    type = HSBoundarySpecifiedTemperature
+    T = ${T_2}
+    boundary = 'coaxial2/shell:end'
+    hs = coaxial2/tube
+  []
+
+[]
+
+
+[Postprocessors]
+  [T_shell_out1]
+    type = SideAverageValue
+    boundary = coaxial1/shell:end
+    variable = T_solid
+  []
+  [T_shell_in2]
+    type = SideAverageValue
+    boundary = coaxial2/shell:start
+    variable = T_solid
+  []
+  [T_tube_out1]
+    type = SideAverageValue
+    boundary = coaxial1/tube:end
+    variable = T_solid
+  []
+  [T_tube_in2]
+    type = SideAverageValue
+    boundary = coaxial2/tube:start
+    variable = T_solid
+  []
+[]
+
+[Preconditioning]
+  [pc]
+    type = SMP
+    full = true
+  []
+[]
+
+[Executioner]
+  type = Transient
+  start_time = 0
+
+  dt = 0.0001
+  end_time = 0.01
+
+  line_search = basic
+  solve_type = NEWTON
+
+  petsc_options_iname = '-pc_type'
+  petsc_options_value = 'lu'
+
+  nl_rel_tol = 1e-4
+  nl_abs_tol = 1e-6
+  nl_max_its = 25
+  automatic_scaling = true
+  steady_state_detection = true
+  # steady_state_tolerance = 2e-7
+[]
+
+[Outputs]
+  exodus = true
+  csv = true
+  [console]
+    type = Console
+    max_rows = 1
+    execute_postprocessors_on = final
+    outlier_variable_norms = false
+  []
+  print_linear_residuals = false
+[]
diff --git a/test/tests/components/coaxial_junction/test.py b/test/tests/components/coaxial_junction/test.py
new file mode 100644
index 0000000..5281641
--- /dev/null
+++ b/test/tests/components/coaxial_junction/test.py
@@ -0,0 +1,65 @@
+"""Python test module for coaxial junction."""
+
+import unittest
+import numpy as np
+
+def heat_flux(time: float,
+              temp_cold: float,
+              temp_hot: float,
+              k1: float,
+              k2: float,
+              rho_cp1: float,
+              rho_cp2: float) -> np.ndarray:
+    """Computes boundary heat flux at junction."""
+
+    numerator = (temp_hot - temp_cold) * np.sqrt(k2 * rho_cp2)
+    denominator = np.sqrt(k1 * rho_cp1) + np.sqrt(k2 * rho_cp2)
+    arg = 1 / (2 * np.sqrt(k1 / rho_cp1 * time))
+    return k1*(numerator / denominator) * 2*arg/np.sqrt(np.pi)
+
+
+
+class TestCoaxialJunction(unittest.TestCase):
+    """Test class for the coaxial junction component."""
+    def test_solid_continuity(self):
+        """Checks the solid temperature is similar on both sides on the solid coupler."""
+
+        time, t_shell_in2, t_shell_out1, t_tube_in2, t_tube_out1 = np.loadtxt(
+                                               "junction_solid_out.csv",
+                                               skiprows=2,
+                                               delimiter=',',
+                                               unpack=True
+                                               )
+
+        # The 2D coupling uses a HTC approach. Here we set it very high: 1e10.
+        # This means that we should expect a small but finite difference between each
+        # side of the coupler
+        # The minimum difference should be delta_t = qw/HTC
+        # qw can be calculated from the analytical solution
+        qw = heat_flux(time, 300, 301, 1, 4, 1, 16)
+        eps = 5e-9 # account numerical errors, set small but arbitrary
+        expected_err = qw/1e10 + eps
+
+        diff = abs(t_shell_out1 - t_shell_in2)
+
+        idx = np.argmax(diff-expected_err)
+        assert all(diff < expected_err), \
+               f"shell temperature difference ({time[idx]}) " \
+               f"greater than {expected_err[idx]}: {diff[idx]}"
+
+        diff = abs(t_tube_out1 - t_tube_in2)
+
+        idx = np.argmax(diff-expected_err)
+        assert all(diff < expected_err), \
+            f"tube temperature difference ({time[idx]}) " \
+            f"greater than {expected_err[idx]}: {diff[idx]}"
+
+    def test_fluid_mdot(self):
+        """Checks the outlet mass flow rate of second coaxial pipe matches inlet."""
+        _, mdot_inner, mdot_outer = np.loadtxt("junction_solid_out.csv",
+                                               skiprows=1,
+                                               delimiter=',',
+                                               unpack=True)[:,-1]
+
+        assert abs(mdot_inner -1) < 1e-4, "Inner mass flow rate incorrect."
+        assert abs(mdot_outer -1) < 1e-4, "Outer mass flow rate incorrect."
diff --git a/test/tests/components/coaxial_junction/tests b/test/tests/components/coaxial_junction/tests
new file mode 100644
index 0000000..365efdd
--- /dev/null
+++ b/test/tests/components/coaxial_junction/tests
@@ -0,0 +1,55 @@
+[coaxial_junction]
+  [test_solid_connection]
+    [run]
+      type = RunApp
+      input = junction_solid.i
+    []
+    [verify]
+      type = PythonUnitTest
+      input = test.py
+      test_case = TestCoaxialJunction.test_solid_continuity
+      prereq = test_solid_connection/run
+    []
+    [run_expansion]
+      type = RunApp
+      input = junction_solid_expand.i
+      requirement = "This system shall allow the coaxial junction to have small changes in geometry"
+    []
+    [check_insufficient_connections]
+      type = RunException
+      input = junction_solid.i
+      cli_args = "Components/jct/coaxial_connections='coaxial1:out'"
+      expect_err = 'must have size 2'
+    []
+    [check_boundary]
+      type = RunException
+      input = junction_solid.i
+      cli_args = "Components/jct/coaxial_connections='coaxial1:out coaxial2:in1'"
+      expect_err = 'Boundary must be'
+    []
+    [check_no_inner]
+      type = RunException
+      input = junction_solid.i
+      cli_args = "Components/jct/connect_inner=false"
+      expect_err = "inner' does not have connected inlet."
+    []
+    [check_no_outer]
+      type = RunException
+      input = junction_solid.i
+      cli_args = "Components/jct/connect_outer=false"
+      expect_err = "outer' does not have connected inlet."
+    []
+  []
+  [test_fluid_connection]
+    [run]
+      type = RunApp
+      input = junction_fluid.i
+    []
+    [verify]
+      type = PythonUnitTest
+      input = test.py
+      test_case = TestCoaxialJunction.test_solid_continuity
+      prereq = test_fluid_connection/run
+    []
+  []
+[]
\ No newline at end of file